Fiberglass Pool Stain Removal & Prevention

Fiberglass Pool Stain Removal & Prevention

Fiberglass pools are beautiful, durable, and often require less surface maintenance than other types of pools. However, there is one common problem that can happen no matter what material your pool is made out of, and that’s staining. In this article, we discuss some of the causes of fiberglass pool stains and how to prevent the pesky blemishes from returning.

Fiberglass Pool Stains 101

I really like the fiberglass pool surface. One of the advantages of a gel-coated fiberglass pool is that it isn’t porous like a plaster pool, and doesn’t become etched and rough. No pool toes, fiberglass is smooth and less susceptible to algae growth and stains because it’s super slick. Nonetheless, gel coat can stain easily.

Stains don’t just happen

There are several causes of stains for a fiberglass surface just like any pool surface. Top of the list are imbalanced chemicals or minerals, high levels of metals or foreign objects can all stain the pool. In my pool, one of the main causes of the bathtub ring around my pool was oily swimmers and sunblock.

Water balance is important

Daily testing can help maintain the optimal water balance. It is best to have a pH balance at 7.2-7.4, and the total alkalinity needs to be at 80-100 parts per million. Maintain your chlorine at or above 1 ppm and the calcium hardness at 200 to 400 ppm. If any of these numbers get out of line, stains can develop. Simply restoring balance to your pool water’s universe is the easy way to prevent pool stains.

How to Remove and Prevent Fiberglass Pool Stains

Use Clean & Perfect enzyme to remove waterline stains

Waterline stains

Culator Metal Eliminator helps remove metal stains

Rust stains

Stainfree removes dirt and organic stains

Dirt & organic stains

Waterline stains:

Before you ban your swimmers from applying sunblock, the bathtub ring can be removed with Clean & Perfect enzyme cleaner to dissolve it before your eyes, naturally. To prevent bathtub rings, try Pool Magic, to remove oily gunk from the pool – it really works! You can also use Comet® cleanser and a kitchen sponge.

Rust stains:

Directly scrubbing rusty or crusty stains with a stain eraser works great, but you can also use a Culator Metal Eliminator. It’s non-toxic and works on well water to actually remove metals from the water, like a sponge. Works with mineral purifiers and copper algaecides, too!

Dirt stains:

If your fiberglass pool has an all-over dirty dullness, ascorbic acid is a great way to safely acid wash your fiberglass surfaces, without draining the pool. Closely follow the instructions when using ascorbic acid, as your pH and alkalinity may need adjustment. Natural Chemistry’s Stainfree is a natural Vitamin C product (ascorbic acid) that gently cleans fiberglass pools.

Organic stains:

Leaves, worms, branches. Running your filter system longer and more frequently during the early swim season while the air is heavy with pollen and tree debris will help to prevent stains from forming on a fiberglass pool surface. In addition to clean water, keep the pool as clean as possible. After heavy storms, remove the big stuff carefully, so sticks don’t get dragged around by a pool cleaner. Again, proper pool chemical balance and sufficient sanitizer is very important.

Identifying the source of the stain is the beginning of recovering your impeccably clean fiberglass pool surface. Once you know the cause there are many simple ways to prevent and remove fiberglass pool stains.

90 thoughts on “Fiberglass Pool Stain Removal & Prevention

  1. Joe Janakes

    Davy,
    Thanks for all the advice. We have a 2 year old Viking fiberglass pool with custom multicolor gel coat to give the illusion of texture. Our Zodiac MX8 tread failed while on one of the steps resulting in the other tread spinning stationary for about a day. The gel coat is intact but we are left with residual black residue about 2.5 feet below the water line on one of the steps. It’s an unfortunate eyesore, any ideas how to safety remove the rubber residue without draining the pool or damaging the gel coat?
    Thanks,
    Joe

    • Hi Joe, most pool stain chemicals won’t remove that, I would try the Stain Eraser, a product that uses friction to rub off stains. If that does not work, you may need to drain down to that level of the floor, to get some solvent on the rubber, WD-40 can work with some scrubbing, or turpentine. Something to break down the rubber, but you have to get it right on there, and you don’t want such chemicals in the pool water.

  2. Eric Klosterman

    Hi, we have a fiberglass pool and this is our first summer having it. We left for vacation for a week and came back to a somewhat dirty pool. We brushed most of the debris to the filter on the bottom of the pool. It seemed like it was just dirt, we then vacuumed the pool and we still have a good amount of black dots on the bottom of the pool. Any ideas on what this could be and suggestions to get back to a nice white shiny pool?

  3. I have about 10-15 small black marks on the bottom of my fiberglass pool. The actually look like small burn/smoke marks. I’ve tried using a bottle of the stain remover with no luck. Any ideas? Thank you

    • Tom, you could try the Stain Eraser, that fits on the pool pole. Would work well if it’s from black rubber shoes or something

  4. I’ve been battling stains/discoloration (below the water line) pretty much since I got my pool. It can be removed with Ascorbic Acid, followed by a sequestrant for maintenance, but it always comes back, even though all levels remain pretty normal (except calcium, which is high in the city water).
    I started keeping track of when these stains show up; they’re not gradual, it’s almost like they appear all of the sudden. It seems to be when the wind kicks up. I live in Vegas, we have massive wind/dust storms, and the soil here is high in its iron content (hence the ‘red’ color, I’d imagine). Is it possible that the wind blowing the dust around gets it into the pool and immediately stains it?

    • Donna, that could be – or it could come from big shifts in water chemistry, after shocking the pool, or making a pH adjustment for example. Are you continuously using the sequestering agent with weekly maintenance doses? The chemical depletes with sun and chlorine, and must be added regularly. Try to avoid shocking, or change to add it slowly, in 4 doses, 4-hours apart.

      • Why do you suggest to avoid shocking? Do you not recommend shock at all? Or if it’s okay when do you recommend? Where I buy my pool chemicals they have me adding shock every week, however that is how they make money, selling chemicals. I have a fiberglass pool about 15 years old and I have that chalky film on the walls when I brush or when we swim and rub against the sides, this makes the water always cloudy and never really crystal clear and sparkling. I see from all the comments the problem is unbalanced chemicals.

        • Hi Rosalie, Shocking weekly is usually way too much. Shocking a pool is done for A-B-C, visible algae, suspected bacteria or chloramine levels above 0.3 ppm. Aside from that, it can be just a lot of wasted money, and more solid dissolved in the pool water. I actually don’t suggest avoiding shocking, but think weekly is usually too much, monthly is probably more correct, in most cases. Your chalky film can be water that is out of balance (pH/Alk/Calcium), or perhaps some effect from shocking. Chalking is usually seen on painted pools, but if yours is not painted, it may be the gelcoat rubbing off, or more likely it is a type of scale deposit that has trouble sticking to the gelcoat.

  5. I have a similar problem as Mitch … black stains in my fiberglass pool. I’ve tried “Stain Away” which did basically nothing. Above, where it says “stainless bristle brush” – does that refer to “stainless steel”? I thought that was only for Gunite pools. Please clarify. Thanks so much for all your help.

    • Yes, stainless steel brushes are for gunite pools only, but when faced with black algae, sometimes we bend the rules. But it could scrape the gelcoat, so use at your own discretion and risk. Try copper algaecide, for black algae. You can also rub the heads with a Trichlor tablet, we have a tablet holder that is used for this purpose.

  6. My deep end has a slight bluish greenish tint, but not the seats that are in the deep end nor does my tanning ledge. It is a fiberglass pool. I have a culater and mineral spirits I also noticed the issue after putting alagacide in. I suspect it is a copper problem just wondering the best way to attack it

    • Hi Sid, I would try our EZ Stain Remover, which can be successful on copper stains. It’s an acid based cleaner, just sprinkle it over the area.

  7. I have a 2 year old dark blue fiberglass pool this spring when we started it up I noticed a white hazy that will not come off. It’s on the fronts of the steps and in several spots over the pool. Since it’s a new salt pool I know we have added very little chlorine manually. Always brushing after adding, all the other basic chemicals have been liquid. Help!! It’s not coming off or up I have tried metal out, mineral out, magic eraser, lemon …… please help

  8. Melia Murphy

    Our fiberglass pool is 15-20 years old we’ve not had any problems until this year when we opened it it has a brownish/yellowish stain all around the water line and on the steps, I tried brushing and the stain away but it’s not working any tips?

    • Try super shocking the pool first, to be sure it’s not organic. If not use progressively stronger acids, in small test areas, to see if that works. Try mineral spirits. Lowering the water level, will be best to get at those, which is likely a mixture of scale, dirt, oils and 10 other things.

  9. Teena Locking

    I have a fibreglass pool and it has rust spots in it, I have had a builder replace a tin roof above the pool and it’s from that just wondering what you would suggest to use to get rid of it , I have used a 3 in 1 stain remover and it hasn’t removed any of it.

    • Hi Teena, if it is spots, and not an overall rust color you are dealing with – that can be easier. Try a “Stain Sock”, where you add a cup of pH decreaser or stain remover granules, to an old, thin sock, and tie it off tightly. Place the bag over the stain, and let it sit for a minute and then remove to see the effect. Easiest to tell, if you are in the pool, with a mask. Another way is to use a PVC pipe, 1.5″, and cut to length, to place directly over the spot, then pour in some granular acid (ph decreaser), and let it sit for a minute, on top of the spot, before removing the pipe. For spots on the walls, attach a 90 fitting to the pipe. You can also use a Jandy Stain Master, to remove rust stains on plaster and fiberglass.

  10. KatieFlorida

    Our fiberglass pool is about 15 years old and likely needs to be re-gel coated. I thought the “smoke” I see when brushing the sides was due to gel loss. Now I’m curious about scale? Sounds like similar symptoms with the chalky stuff coming off. I’m going to try your recommendations for treating scale. If it does require reapplication of gel coat, is it possible to just put a liner in a fiberglass pool? What all does this involve? Does there have to be some form of coping around the top of the pool? Ours does not have this coping.

    • While it is possible to put a liner in a fiberglass pool, I would not recommend it, and the cost would make you gasp. If scale treatment does not work, You could drain the pool by a few inches, and acid wash the side walls, with a 50/50 muriatic acid mix, poured from a flower watering can, and rinsed off within 60-90 seconds. If the surface improves, do the whole pool. Or another option is to paint the fiberglass pool with epoxy pool paint, which only lasts 5-7 years, but is a whole lot easier and cheaper and DIY friendly, than gelcoating the pool.

  11. Veronica Villasenor

    I have an organic stain we left the leaves too long at the bottom of the pool. I would not be able to drain the pool to access the stain area? It’s about 8 feet deep. Any chemical strong enough that you would recommend on getting rid of the stain with that drop in the pool level?

    • Hi V, sure, first try regular pool shock, sprinkled over the area. That will remove most organic stains instantly. A low 7.2-ish pH is best for most chlorine potency

  12. Mitch price

    I have a fiberglass pool and there is black spots on the side of the pool walls. I need help in getting rid of the that nasty stuff. Please help

    • Hi Mitch, black spots, sounds like you got the algae. First thing is to check pH level and adjust down to the lower range, around 7.2, and check it every day during treatment, to make sure it didn’t pop back up. Low pH makes chlorine more powerful. Run the filter 24/7 if possible for now, and get in the pool with a plastic pancake flipper or putty knife, and scrape the heads of the algae, trying to scrape them off, but being gentle with your gelcoat surface. Use a stainless bristle brush and go to town on the spots, going over each spot several times from a few angles, to score the surface, and disrupt the protective surfaces. Brush them all, 2 or 3 times, really hard, with gusto. Then shock the pool with a double dose of Super Shock, our strongest 73% available chlorine shock, then brush again in the morning and recheck the chlorine and pH level. Then shock again, a single dose this time, or 1lb per 10000 gals, and brush the pool again. After brushing, shocking, scraping, vacuum clean the pool, clean the filter very well. If possible to lower the water level a foot or so (don’t drain fully) to expose the heads, you can get a pressure washer on them, which is quite effective. Also if possible, replace your filter media; sand or cartridge, or for DE, open it up for a complete cleaning and soak the clean de grids in a 10% bleach solution.

  13. Karol Faurie

    Do you know anyone that will refinish or do gelcoat on a fiberglass pool in Illinois? I have chalky residue when rubbing on the walls of the pool. Also blue staining that will not come off.

    • Hi Karol, I don’t know, but I would start with fiberglass pool builders in Illinois near you, who may provide such services, or have a referral for you. Second idea is to contact Boat repair companies, which usually work in a boat yard, repairing fiberglass boats, but may have a travel service. Third is auto body repair companies that specialize in Corvettes and other fiberglass cars or kit cars. The chalky residue may be a result of imbalanced pool water, pH, Alkalinity and Calcium Hardness levels, and adjusting these may remove the chalky residue.

  14. Rich Bakir

    Our Fiberglass pool is less than a year old. After a couple months the entire surface of the pool is covered in a white foam that will not rub off. Almost like it oxidized. I tried an entire bottle of scaletec with zero results. Help!!! I tried scrubbing a small area with a magic eraser and it helped slightly. Is the gel coat oxidized? What do I do? Our pool looks terrible!

    • It could be scale, as you first suspected. You could test an acid solution on the surface, by lowering the water level a little and pouring a 50/50 mix of muriatic acid/water, from a watering can or spray bottle, onto the surface. If it fizzes and dissolves it is calcium scale. Probably not oxidation. Scaletec can take a few weeks to see noticeable results.

  15. Robert Murphy

    I have a question. I have a fiberglass pool. I painted the concrete around it and then the edge facing down to the pool. I had some paint drops fall in the pool as I was working. It is water cleanup. I didn’t notice much till three days ago. A rough not removing easy stain around pool. Like a white water line. I tried car wax, fiberglass cleaner for boats ect. I tried mr clean eraser, ect. Any suggestions?

    • Hi, you could try some mineral spirits or paint thinner. Do a small test area first, and allow it to dry for a few hours, to be sure it won’t remove the gel-coat on the fiberglass!

  16. Benedict Londt

    Good Day,
    I’m residing in Gaborone Botswana, originally from Cape Town(SA)I moved into a house here in Gaborone where the Fibreglass pool was not cleaned at all for my years, algae, dirt, green water you name it was the order of the day. We finally managed to clean the pool, with clean water chemicals etc, everything is in good condition, its just I have like algae stains in the corners, at the stair area, between the stairs, the pool is clear except for these stains which really looks as if the pool is not swim worthy, if you could assist – how do I remove these stains permanently?
    Thanks, Benny
    (+267)74 – 909 970
    (+267)72 – 261 637

    • HI Benny, it could be hard to clean without emptying the pool, and exposing the stain to direct chemical treatment, but some things to try might be: 1) wet/dry sandpaper, lightly sand the surface in a test area, or 2) add some granular chlorine in a test area, or 3) add some pH decreaser (dry acid) in a test area. If the surface of the gelcoat is stained, it can often be removed with the methods above, but if the stain is in the fiberglass fibers, then it may be very difficult to remove. Many stains of this nature will lighten with time as well, especially with well balanced water and high chlorine levels, and regular sun exposure, and good cleaning practices, especially brushing the area often.

  17. Karen Torrence

    I stumbled onto your blog and thought I would reach out to you for advice. We are in our 17th summer with our 16×35 white fiberglass pool. Two seasons ago, after opening the pool for the summer season, we noticed that the sides felt a little rough like they needed a good cleaning. I used a soft cloth and wiped down all sides of the pool as far as I could. The water turned completely cloudy while wiping the sides. It took a lot of vacuuming to waste, filter changes and clarifier to get the water clear again. One pool store told us we needed to raise the calcium level in the pool which will lock in the gelcoat. Another company said we need to drain and re-gelcoat the pool as too much chemical had eaten away at our gelcoat. Seemed like these two solutions were opposite of each other so we did nothing. The pool is rarely used by swimmers (used mostly for floating on a raft) so when we have swimmers who rub against the sides causing the chalking and cloudy water we just vacuum to waste and use clarifier to clear it up again. What would you suggest for a solution to this issue?

    • Hi Karen, it is chemistry related, from low calcium hardness and possibly also low pH/alkalinity. Balance these two levels and then the problem should subside. If you can, you could pump out 1/2 the water, wipe down the walls, refill with fresh and then rebalance pH, alk, calcium, stabilizer levels.

    • Sounds like your pool needs to be refinished with new gel coat. Not many companies deal with this, so good luck. We had our refinished and the chalky, cloudiness is a thing of the past.

  18. I have a fiberglass salt water pool with a gelcoat surface. Recently I noticed brown-ish coloured stains on the bottom of the pool. There are 3 areas, and they are similar in size. The stains are grouped together and look almost like worms. We are on well water, have a safety cover and always open with a green pool which we treat with algaecide and shock etc. Water was just tested and hardness is low (44ppm) and Alkalinity is low (63ppm). Phosphates are always high. Any idea what this stain is and how to go about getting rid of it? Many thanks!

    • Hi, they could be worms, not unusual with spring start-ups. Could also be some type of other winter debris. I would first balance the water, to bring up calcium and alkalinity and recheck pH level, then sprinkle 1 lb of shock over the area. Let stand a few minutes then brush off. Repeat treatment after 12 hours if it helps. You can also try one of our stain removers, EZ Stain remover or A Plus Stain Remover. Being on well water, you should also use a sequestering agent like Stain Away, on a regular basis, to keep metals and minerals locked up in solution (if you are concerned about possible staining).

  19. I have a fibre glass pool with a self cleaning system. The pool is well maintained all year round, however recently dust has been sticking to the walls of the pool. I have to manually brush down all the walls only for it to return a few days later.

    • Hi Megan, that could indicate some construction or agricultural dust in your area, likely temporary. It could also mean that your pool filter media is tired (sand, cartridges), and may be time to replace, or use a Filter Cleaner. You could also try a pool clarifier, which may work well for particles that seem to stick on the walls, as though static cling, the clarifier attracts them and allows your filter to trap the larger clumps.

  20. Renald Piché

    Hi, I have a 16′ x 32′ inground fibreglass pool that is seven years old. When we touch the walls, we come away with a white film on our skin, as if the paint is coming off the surface. In effect, the pool is white in color and we have a salt chlorinator. Can the salt have caused the gell coating to disappear?

    • Hi Renald, is your pool painted? A fiberglass pool can be painted, and with aggressive water conditions, from high chlorine or low pH/Alkalinity, it can ‘chalk’ or come off as you describe, on fingers and toes. It would take much more of a water problem to affect unpainted fiberglass, or to cause a gelcoat to chalk, but it is possible I suppose. Salt water does not normally damage gelcoat on fiberglass pools. It could be a scaling condition, in cases of high pH and high calcium, or other cases, where calcium films can coat pool walls and floors. If you

  21. Charlie Blythe

    I have a 8 month old dark colored fiberglass pool. Recently I noticed some discoloration along the bottom of the pool. It is almost in the pattern of how the robot cleaner cleans the pool along the bottom. The discoloration is light, almost hazy. I have tested for metals and tried the stain remover even though it tested negative….which did not do anything. It will not scrub off and does not feel pitted or anything. Any other suggestions?

    • Hi Charlie, does it seem like the area is worn? Not sure if the cleaner would do it, but if the tracks or treads are particularly sticky, maybe it is wearing the gelcoat in those areas from the friction? With most stains I like to try 3 chemicals, first sprinkle shock chlorine over the area, or deliver it to a spot by pouring it into a PVC pipe. If that doesn’t work, after I would try ascorbic acid, like StainFree or our A Plus stain remover, or just ground up Vitamin C tablets, which can be used as a test. Sprinkle over the area, or deliver with PVC pipe (or pool pole half). Third thing would be a stronger acid like the EZ Stain Remover, again sprinkled over the area, or placed into a thin sock or hose as a ‘stain bag’. If none of those works, you could try rubbing with wet/dry sandpaper in a small test area… Throughout it all, be sure that water balance, filtration and chlorine levels are all maintained well. Good Luck!

  22. Hi guys would appreciate help.

    Bought a house with a beautiful Roman fiberglass pool. I was having trouble keeping the pH up. I assume from using trichlor tablets for chlorine.

    Being new to pools I kept trying to read and learn. In an effort to balance Ph I dropped the chlorine down and developed some black algae blooms. I put some algaecide in and I began shocking pool once a week per suggested by my reading.

    I then found that I had been treating pool for 10k gallon pool. And I have a just under 20k gallon pool.

    So the next week I doubled the shock treatment since each package was for 10k gallons.

    That weekend (this past one) I noticed a brownish Haze at the water line. I didn’t think much of it. Monday we got a lot of rain and the next day I noticed the brown had settled in the steps and the side that gets the most return flow and along the deep end wall.

    I was not happy. This pool had been beautifully White for over a month.

    I tested and chlorine was high, pH and alkalinity low. I then treated with 24 pounds sodium bicarbonate and circulated for 24 hours. Tested and chlorine was perfect, pH and alkaline now ok. I added metal out and circulated for 24 hours. It seemed to help some.

    I then added 2 qte of Jack’s blue stuft and continued circulating. Say some improvement but top step that gets less circulated and one wall and deep end remain stained.

    Since Thursday have been making sure water is balanced.

    Any thoughts on how to proceed to remove remaining stains?

    • Hi Steve, try using Ascorbic Acid (Vitamin C) on the steps, you can test with crushed up Vit C tablets, and if it works, buy our A Plus Stain Remover, or StainFree, or StainFree Extra Strength, to apply over the area, following label instructions. Generally the Vitamin C works best with metal/mineral stains, and our Stain Eraser product works better with organic stains. All can be found on our Stain Removers page.

  23. MaRia Binks

    Hi, I just had the pool surround sanded and resealed and some was spilt into the fiber glass pool onto one of the seats under the water. Some of the dust has set into this sealant and Im not able to get it off. Any suggestions to how I should do this please? Its a salt water pool. Thanks

    • Hi Maria, I would think that you could use whatever solvent would work for the sealer, but would need to lower the water level below the area, and apply carefully with a sponge or something, testing in a small area, maybe using xylene or xylol, or paint thinner and a toothbrush or rough rag? I’m just guessing here, this is not a common issue. If you know the brand name of the sealer, the manufacturer may be able to provide better guidance.

  24. Larry meyer

    We have a 10,000 gal fiberglass pool. Opened the season with a bad case of algae. Once we got that cleared and vacuumed and pool all balanced about 7 days later we developed a darkening of the pool walls from 4”below the waterline to the pool bottom. Seems to have some texture but can’t be rubbed off. Need suggestions for the next steps. TIA

    • Hi Larry, given that the stain has ‘texture’, I would assume this to be a calcium scale (mixed with other colored junk). You could try a no-drain acid wash, by lowering the pH to about 6.5 for a few days, to see if it will dissolve with some brushing. Adding a sequestrant like Scale Free or our Stain Away, can also help put the minerals back into solution. Another route or test would be to lower the water level a few inches below where the stain starts, and use a flower watering can to pour a muriatic acid mixture 50/50 on the pool wall, rinsing quickly afterwards, within 30-60 seconds. If that works best, you may want to drop the water close to the floor and pour the entire wall, and the resulting low pH level in the remaining water may also clean up the floor.

  25. Reading through the comments i wasn’t able to find a similar situation to mine. After opening our fiberglass pool and doing the initial steps to get it ready for summer, i noticed stains at the bottom of the pool. During the winter season i dropped chlorine pucks directly into the pool rather than putting them in a floating device. Now i have yellow, perfectly round stains on the pool floor. I have already tried vitamin C tablets, but that didn’t work. I put chlorine pucks in a sock and let them sit on the stains and then tried scrubbing, that didn’t work either. Can you please guide me in the right direction? Thanks!

    • Hi Manny, those stains may be permanent, more or less. I call them chlorine ‘burns’, rather than stains. Sanding the surface with wet/dry sandpaper or using a Stain Eraser or pumice stone can help to remove some of the burnt orange … burns on the surface but will result in a lighter area underneath. A more radical repair would be to drain the pool, grind off the gelcoat and reapply over those spots, which may not match perfectly.

  26. Jessikah

    We have about a 30,000 gallon fiberglass pool we have dark stains in deep end where wall and floor meet and then tea like stains in center some rust spots that look like metal objects where left in water. We bought a foreclosued house that had sat vacant for 3 years we got pool up and running but the stains are ugly. We used magic eraser which didn’t work much at all.

    Next question pool has a fiberobtic light the box that held the electric stuff was completely smashed and broken how can we replace light for pool ? Thank you for any help! We are new pool owners and very confused

    • Hi Jessica, for the stains, first balance the water (ph, alkalinity, calcium), and then shock the pool with granular chlorine, to remove any organic staining. For remaining stains, follow-up with our EZ Stain Remover, sprinkled over the stained areas, following label instructions.

      For the fiberoptic light – the smashed box will need to be replaced, if available – some very old systems are no longer made, look for identifying manufacturer and model numbers, and then do a google search for the ‘tower’ or ‘photon generator’, as they are sometimes called. If not available, you could convert to an LED system, assuming your lights are in 1.5″ wall niches, you could use SAVI lights or other 1.5″ LED lights, connected to a new control system, mounted by the pump and filter equipment.

  27. Ted Collins

    I have a fiberglass unground pool, roughly 15k gallons. I had algae at opening but was able to clean that up. Struggled to get the pH into proper range (free chlorine and alkalinity were spot on) and when I did, I got a waterline to pool floor reddish brown stain that cannot even be power washed off!!
    I am not sure what to try as the water testing showed no metal content in the water.
    Help!! What would you suggest?

    • Hi Ted, I would still suspect metals, which can test for zero, if metals have already deposited on walls. I would try a sequestering agent, like Stain Away or Jack’s Magic Purple Stuff, or Blue Stuff, or Metal Free – lots of brands that lock up minerals and metals into solution. Not usually used for stain removal, but in certain instances, timely treatment can actually dissolve (slowly) the metal deposits. Reddish brown stain sounds like iron…

  28. Ryan Murphy

    Hello, I have a dark blue fiberglass pool that was installed last July. I had masons install the pool coping late August/September and now there are white effervescence drip lines, from the cement, from the coping down to the waterline of the pool. Any ideas of cleaning it up?

    • hi Ryan, first check the water balance, especially calcium hardness levels, to be sure that the water is not seeking calcium from the coping mortar. Cleaning it up is usually done with a muriatic acid mix, poured over the area and rinsed off after it stops bubbling. (afterwards, you will need to raise the pH level, if much acid (ph decreaser) is used). Prevention may involve sealing the face or pool side of the mortar, but if water is coming from behind, and seeping thru the front, some method of stopping or diverting water away from the backside of the coping may be necessary.

  29. Hi,
    We have a saltwater fibreglass pool.
    Our chemicals were recently incorrect and it has caused our zodiac barracuda cleaner to leave a sticky residue in the corners of the pool and also to have a sticky substance on the cleaner itself. Any idea on how to get the sticky residue off the pool please?

    • Davy Merino

      Hi Melissa, an enzyme pool product would be my first choice. Natural Chemistry makes several, Pool Perfect is the main one… but I see we only sell it in a giant $45 bottle. You could use the Pool Magic or Pool First Aid. Both under $20. After adding, I’d brush the areas well with the pool brush, maybe switching to a textured sponge or softer bristle brush.

  30. We just had a fiberglass pool installed and when vacuuming all the dirt out, the pool got scratched. Is there a way to fix the scratches?

    • Davy Merino

      Hi Nancy, if they are small surface scratches, they can be blended with a fine wet/dry sandpaper. Deeper grooves can be filled with gelcoat and buffed with the pool empty. I’ve not much experience in gelcoat repairs, but it’s similar to boat or corvette scratch repair, or pool slide repair.

  31. Stacy Hinkle

    Hi Ryan!
    We purchased a fiberglass pool we are still waiting on Concrete to be done. We had it running for couple weeks know but we have this black ring forming around water line and all the walls and sides of steps. We had the water tested they said all ok. Could you let me know what chemical would be safe to put in to clear up?

    • Davy Merino

      Hi Stacy, I would go with an enzyme, if the black ring is oily and rubs off with a little effort. Natural Chemistry products like Pool Perfect, Pool Magic and Pool First Aid, are different blends of enzymes and stain removers.

  32. I have a fiberglass pool approx. 15,500 gallon. I have a stain that can be removed by rubbing crushed vitamin c on it. I have my water tested at the pool chemical store, it has tested 0 for metals. I brought the chlorine down to 0 and my alkilinity and PH were in suggested range. I used 1 bottle of Stain Out and the stain lightened on my steps but not on my entire pool. A week later I used another bottle and let it circulate for 24 hours. No results. A month later I tried asorbic acid. I used 1.5 lbs and saw no visible results. 1 hour later I added another 1.5 lbs and let it circulate overnight,slight if any results. I do not know what to try now. Any suggestions?

    • Davy Merino

      Hi Deneice, I’m not familiar with stain out, but it may be either an acid stain remover like our EZ Stain product or a sequestering agent to tie up metals, like our Stain Away product? The Vitamin C tablet test went well, but treating with ascorbic acid (vitamin c) did not help too much? We do have StainFree Extra Strength, which may do the trick. have you tried shocking the pool with chlorine shock? If the stains are organic, oftentimes shock will remove instantly. And if neither ascorbic acid or chlorine removes the stains, the next step would be to lower the pH to 7.0 and use EZ Stain remover or similar acid to attempt a ‘no-drain acid wash’, broadcasting the material (expertly) over the entire surface areas, with the pump off. You might need 2 bottles for the average size pool. Brush the pool after a few minutes, very thoroughly and raise the pH back up after 4-8 hours or overnight, and turn the pump back on.

  33. Crecencio Sauceda

    I have a white fiberglass pool that turned dark brown. You can rub it off but takes some scrubbing to do so. What can cause that?

    • Davy Merino

      Hi Crecencio, likely an iron issue, if you have iron in the water, it can come out of solution and deposit on the walls. I would try using our EZ Stain remover product, or something similar, following instructions closely, and then treating with a Metal Free type of sequestering agent to keep it in solution. You can also have your water tested for metals, or buy a test kit of your own to narrow down the metal, but it’s usually iron when brown or red.

  34. Michelle M. Arnold

    Hi! I am a Realtor and my clients are considering purchasing a foreclosure that has a Fiberglass pool. We live in Yuma AZ where it is currently 114 degrees. That means that the pool went Green while it was in foreclosure status. It is now cleaned up but heavily stained. do you have any recommendations on stain removing? I wondered if it is similar to a bathtub, can it be drained and then put soft-scrub with bleach on it and let it sit for 24 hours? Any suggestions you can offer would be appreciated! 🙂

    • Hi Michelle, must be awful for the buyers. It is similar to a bathtub, with the exception that there could be risk in completely draining a fiberglass pool, due to unforeseen and unseen problems underground, or some flash flooding, etc. Not that you can’t drain it, but does contain risk. I would first try to make sure that the pool water is impeccably balanced, and truck in water if that was necessary, replacing most of the current water, to have excellent water balance. Then you could treat the stains, with water in the pool with two types of acids that are just sprinkled in. StainFree or our A+ Stain remover are ascorbic acid, great for fiberglass stains. EZ Stain remover is another acid that will target other types of stains. If you have ‘algae stains’ presumably, I would start with EZ Stain. If the stains are suspected to be mineral/metal stains, from aggressive shocking, start with A+ Stain…. The Softscrub would work if it was live algae, but likely it is not…good luck!

  35. Christina

    Hi, We purchased a house that already had a fiberglass pool installed at the time of purchase the water was clear but after swimming in the pool the next day we found a dead gopher in the pool and the water was a dark greenish brown color. We took a sample of water and had it tested and the alkalinty was at 200 ppm, the PH was at 7.8, cynuric was at 40 ppm. So i was told to shock it with 1 pound of unstabilize tri-chlor. After adding the tri-chlor we were told to add 1 gal of liquid chlorine 2 days later. The water then turned into a reddish brown color and was told to put 2 pounds of sodium dichlor then brush the pool then add a pint of muratic acid then they told us to add calcium hypochloride 2 hrs later then clean the cartridge filters. It has been 4 days now and the water still looks reddish brown but when we brushed the pool it still doesn’t come off could it be that our fiberglass pool is stained now. What can we do to fix this? Thank you

    • Hi, it sounds like the shocking of the pool, with a high pH caused metals (iron) to come out of solution, and turn the water that color. The solution is to get the metals back into solution, nice and quietly – shhh! Use a sequestering agent, like jack’s magic blue stuff, metalfree or stain away, to lock up minerals in solution. Before adding however, lower the ph and alkalinity, with pH decreaser, to get alkalinity below 150 ppm, but keeping pH 7.2-7.6. After the sequestering agent is working, you may have some stains remaining, as you mention you have now, Jacks’ Magic Stain Solution #1 (the Iron/Copper Stuff) can be used, or EZ Stain Remover or StainFree or our own A+ Stain remover could also be used. Alternatively, if you can drain most of the water and refill with fresh water of a lower mineral/metal content, that may also ease the entire process. You may be on a well, which is common to have high mineral/metal content. There are pre-filters we sell, attached to a hose, for filtering out minerals/metals and other gunk. For pools with metals or hard water problems, a sequestering agent should always be used, in maintenance doses (every week or two), because it degrades in 1-3 weeks time, and replacement protection is needed. If you are not on well water, and have iron/copper issues, some public water systems do have high mineral/metal content, or there may be another problem like a copper heat exchanger or pipes, iron headers or pipes or steel ladders and dive stands, putting oxidized metals in the pool…

  36. Michael Cline

    Good afternoon. We have a Viking pool that was installed 4 years ago. This year, we’ve experienced scaling. We have been using Scaltec to help resolve with little results. The rich pacific color is diminished. What can we do to resolve?

    • Hi, first be sure that your pH and alkalinity are on the low side, 7.2-7.4, and 80-100 ppm. Calcium hardness levels should be 150 ppm minimum.

      You could do some regular LSI calculations – using the Pentair Langelier saturation index – and adjust your chemistry away from the scaling range, to the corrosive range, and brush daily. Having slightly acidic or corrosive water conditions and heavy brushing can help remove the scale, but it can take time. Use a sequestering agent like ScaleFree or Stain Away concurrently, to lock the minerals into solution, once they are removed from the wall.

      Alternatively, you could lower the water a foot or so and test an acid wash, by pouring a 50/50 mix of acid/water, from a flower watering can, along the edge of the wall. Rinse within 60 seconds, thoroughly. If it removes the scale (repeat treatments may be needed), then draining and acid washing the entire pool may be the ticket.

      Following treatment for removal, keep your water balanced, and always use a stain & scale chemical, to keep calcium and other minerals/metals, in solution, so they won’t be tempted to deposit on pool surfaces.

      • Michael Cline

        Thank you for the advice. One last question, is it safe to drain a fiberglass pool. There seems to be several myths out there and I want to be sure the pool or decking would not be damaged. I would not attempt this myself, rather hire a professional service.

        • Hi Michael, yes it is safe, but can cause trouble. I have drained many fiberglass pools and never had a problem, but the risk does exist that without the water in the pool, the shell could shift or raise up slightly, or weak walls could bow inward. Key is to pump the water far away from the pool, and avoid very wet weather periods. Problems with draining a fiberglass pool are rare, probably less than 1%. Hiring a pro is best, assuming they have the insurance policy to cover any problems.

  37. Bernel Nery

    I have a resurface fiberglass pool that was installed back in 2007. I have aprox 24k gal like kidney shape, 3.5 feet shallow and 9 feet deep. Per my pool guy my gel coat is coming off in the some spots in the shallow area. Those areas look like light green stain, I would have thought they were algae but my pool guy says they are fiberglass exposed and they look like that. I recently installed a DE filter as my upgrade from cartridge type. I have tried brushing them with both rubber and normal brush but they wont come off. I was told brushing them will cause more gel coats to come off. I use a classic kreepy krauley as my daily cleaner. Sometimes I wonder if the Kreepy Krauley is a culprit. I would like to hear your opinion. I can probably post pictures if needed.

    • Davy Merino

      Hi bernel, The Kreepy could be a question, if those areas are bulged or raised, or a depression of just the right shape, the Kreepy could get stuck, and suck and suck on the area, but you would probably notice that if it was happening. It could be a delamination between the fiberglass shell and the gelcoat, which may be under warranty, perhaps. The gel coat is the same stuff used on pool slides, boats and fiberglass cars. A shiny ceramic like gel is sprayed onto the fiberglass, about 2 mm thick. It does wear away over time, but not usually so fast (10 years). The stain could also be caused by a ‘chemical burn’, from tablets, shock or pH down (something caustic) laying on the floor in those spots? I may not be too qualified to help, as I have not a lot of experience with fiberglass, but you can send pics to swimmers@intheswim.com, and I should receive.

  38. Billy Mitchell

    I have a pretty blue ring at the water line and what appears to be blue splashes on the steps. What is cause and remedy?

    • Davy Merino

      HI, I’m not sure, but could it be from copper algaecide? Pool Party blue pool dye? Not many things make a blue stain, but sounds like something got in there. I would lower the water level and apply TSP with a scrub brush. Maybe automotive rubbing compound also would rub it off. A paste made from Ajax or Bon-Ami and water, rubbed in with a scrubber sponge may help. You can’t be too harsh with the gelcoat, but an acid would also be a possibility. You can scrub with vinegar, followed by baking soda. You can also use granular ph decreaser (dry acid) or EZ Stain Remover, in a sock, and with gloves and water, scrub the wall with the stain sock, and the steps, or just set it on the steps underwater for 30 seconds. Ascorbic acid can also be used, in products like StainFree and A+ Stain Remover.

  39. Dale boss

    Fiberglass pool : added liquid chlorine: recently added all new water: plaster now has developed black staining thruout : added metal out when pool was refilled recently : ph a little low added soda ash: get rid of black staining: add more metal out ? Perhaps raise ph a little more ? Add stain out treatment? Small pool

    • Hi Dale, what may have happened is copper or other metal dropped out when shocked. That has happened to me on pools I was overdosing with copper algaecide, and a sequestering agent like Metal Out or Stain Away, can help prevent it. I also stopped using copper algaecide. For your pool, test for metals if you can, to see what you are dealing with. If the black stains responded to the Metal Out, I would keep the pool on a maintenance dosage for awhile, usually just a cup or so per week, because sequestering agent bonds can weaken in certain conditions, and shocking the pool can knock the metals out of solution (again). If there are still stains, you can try EZ Stain Remover, a granular acid.

  40. Hi. I have a fiberglass inground pool. A few months back, I got sick. When I returned home, the water level evaporated to half it’s normal fill. I’m guessing that combined with our high calcium water levels, left heavy scale on the bottom of the pool.
    I’m wondering would the Vit C fix, work on the scale? The reason I’m asking, I’m looking at the NUVO water softener system to use in my house to control scale. It stops and reverses scale (supposedly). The system uses Vit C. Seems similiar. Thanks.

    • Hi Dave, Vitamin C or ascorbic acid, is an acid, so it can effectively remove scale by dissolving it – Stain Free and A+ Stain remover are two ascorbic acid stain removers that work on many stains quite well, and should have some effect on the issue you are having. Follow label instructions for water balance and application, etc. To test it first, you can grind up a handful of vitamin c tablets and place them on a sample area. You will also need stain & scale (sequestering agents) like Stain Away, to lock up the minerals, because dissolving them does not remove the calcium from the water.

      • What can I use to stop the staining from coming back?

        • Davy Merino

          Hi Ed, there are things you can do, depending on the type of stain. If it is from minerals or metals, start treating weekly with maintenance doses of a good sequestering agent like MetalFree, ScaleFree or Super Stain Away. If it is an oily, organic stains, using a maintenance dose of pool enzymes like pool perfect can prevent those stains. If the stain occurs from some outside source, or contamination of the pool, stuff getting into the pool, then you can develop a plan to reduce or eliminate, whatever is causing the stain. (assuming that you know)

  41. mary jane delorey

    Hi I put in all the chemicals the pool store told me to, after having my water tested. I put in stabilizer, alkaline increaser, PH increaser. Now my white fiberglass pool is turning yellow. Any suggestions
    Thanks

    • Yellow algae? Does the color brush off at all? If it won’t brush off, it’s not likely to be algae. I would shock the pool, to raise the chlorine level above 10 ppm, brush well, and filter well. Yellow algae may also require a filter media replacement, recommended for yellow algae blooms, and a treatment of algaecide on a regular basis.

  42. Sharon Delaney

    Hi Ryan, I have a salt water fiberglass pool. Last year when we uncovered it there was a square patch on the side of the pool. It was dark grey in color we were not able to get rid of it and my husband convinced me to just live with it. This year when I uncovered the pool there are two more stains the same color but they are about a 5 in he circle one right above the other. Any suggestions what this could be or who to call? We live in Myrtle Beach SC. Thanks!

    • A circle and a square? are they perfectly round and square? that could be a clue. I’m not sure what this could be, but perhaps trying a Jacks Magic Stain ID kit may turn up something. I wonder if it may be something visible on the fiberglass shell, beneath a thinning gelcoat? Stains don’t normally form such shapes, in isolated locations, especially the wall.

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