Cloudy Pool Water Issues


As a former pool store manager for over a decade you can trust that I’ve heard my fair share of “My water’s cloudy, what can I do?”  In fact it was the number one issue – day in and day out.  And it was my job to figure it out.

There would be folks waiting in their cars before we opened and pounding on the door after we closed, with water bottle samples in hand, looking for solutions to their cloudy pool water problems.

Keeping a pool clear for most pool owners can be a struggle, especially new pool owners; those who get improper advice or follow the wrong procedures, or when you start with an especially yucky pool from the get-go at opening.

So what causes cloudy pool water, what are the remedies, and what is the best preventative treatment to keep your water sparkling clear?

CLOUDY-POOL-WATERPOOL OPENINGS: Some common causes are simply part of the pool opening process. After not filtering for six months, what would you expect?

What often happens is when you have a solid cover for your above ground or in ground pool and you don’t pump every last bit of the yucky water off the top, so that when you try to remove the cover, the last 10+ gallons of nasty water that’s saturated in leaf debris, tannin, algae, and bugs is too heavy to lift, and ends up in the pool! That concentrated slimy water hits the pool and explodes outwards and clouds up the entire pool in a matter of seconds so that it looks as if you may as well have not covered it at all.

Afterwards. it’s on to spending a small fortune on shock and chemicals, hours of vacuuming, and scooping out leaves. Wasting water backwashing or rinsing down cartridge filters. All of which is what you need to do to turn the pool around when this happens. That used to happen to me every other year until I purchased a nice lightweight safety cover that’s a snap to lift off because water and snowmelt drains through and the leaves blow away.

CLOUDY-POOL-WATER-2MINERALS & METALS: There are other ways a pool can cloud at opening for instance simply topping the pool off can be a potential problem for some. Untreated well water is often used by rural pool owners and can be laden with minerals, iron, and other metals, that have soaked into the ground and ended up in the well. These things can leave a brown tint to the water and leave orange rust deposits on your skimmer & pump baskets, trim frames and ladder bumpers, liner, and just about any pool surface. If left unchecked, these can be a source for murky water and lead to permanent stains.

A garden hose filter is a handy device for pre-filtering minerals and metals. It’s an inline strainer that you thread onto your hose that absorbs iron and scale before it can get in the pool.  Another remedy is to apply a stain and scale remover. Many brands are available that sequester or chelate (from the Greek word for claw) out the metals so your filter can trap them, while an acid in the chemical formula breaks down scale (calcium). This product should be used whenever water is added to remove metals and break down scale, and is often included in opening and closing kits for pools.

HAZY-POOL-WATERWATER BALANCE: Another common occurrence is to have unbalanced water with unusually high or low pH, Alkalinity, Calcium Hardness, Stabilizer (cyanuaric acid), TDS (Totally dissolved solids), or chlorine. You may have any one high and another low or a combination of all of the above being out of whack. A good rule of thumb is that anything high can cloud a pool so bring down the levels to the low end of their range.

Another rule of thumb is to balance Alkalinity First, and then move on to pH next. Alkalinity is increased with Sodium Bicarbonate and reduced with Muriatic Acid. Low pH can be adjusted with Soda Ash, high pH with Muriatic acid or Sodium Bisulfate. Calcium hardness is increased with Calcium Chloride and reduced with a stain & scale remover. Cyanauric Acid is reduced only by draining and replacing water. Note that sometimes high CYA causes cloudiness and sometimes it does not.

High TDS can contribute to cloudiness and should be within the recommended range in the manuals for mineral systems, Power Ionizer, and salt system owners. TDS is essentially anything dissolved in the water except H2O. The acceptable range is wide at 0-2000 ppm.

So once you have tested and balanced these things and cloudiness still persists, then we must explore some other scenarios which I will try to explain without any opaque utterances, so that you can have a clear understanding.

TURBID-POOL-WATERTOO MUCH SHOCK? One such scenario is over-chlorination and over-shocking which often leads to doing more harm than good.  I had many a customer dumping more and more chlorine & shock in their pool to try to clear it up not knowing that this process can temporarily cloud the pool as a side effect of doing its job. And if you don’t wait between treatments the cloudiness just overlaps the next treatment so you never get any results. Like taking two steps forward and three steps back. Some people would go all summer without ever clearing up the pool because they didn’t wait between treatments.

Another mistake that goes hand in hand with this is to measure your chlorine too soon after shocking. What happens is that the chlorine is so high that it “bleaches” out the test. Test strips and residential reagents are not designed to measure extremely high levels of chlorine and the super-chlorinated water literally bleaches out the test strip pad or disintegrates the reagent in your test vial so it appears there is no chlorine in the pool and the homeowner hits it with more chlorine and more chlorine making it more and more cloudy. That’s when it’s time to stop, wait, test, then shock with the right dosage.

Shocking the Pool for Cloudy Water

CLOUDY-POOL-WATER-2Nine times out of ten all you need to do is shock. But – you need to dial in the correct amount. And when you shock the pool, do it properly to reach what is called breakpoint chlorination. What this means is that you are going to raise your chlorine level to ten times the level of combined chlorine.

Combined chlorine is the accumulation of chloramines or chlorine that has attached itself to organics such as algae to suffocate it, ammonia from oils, debris, and bather waste, and all of the yuck that fell in from that solid winter cover mishap at opening.

Combined chlorine = Total Chlorine – Free Chlorine. DPD test kits will test for combined chlorine, while OTO test kits and test strips will only test for Free Chlorine levels. Chloramines build up in the pool until you give it a good shocking to burn or oxidize it away.

OXIDATION: What is oxidizing and where do the chloramines and yuck go? Pour too much bleach on a shirt and what does it do? It eats a hole in it right? Where did the material go?  Poof! It’s just gone! Well that’s oxidizing. Some call it “burning off.”

Now, the amount of pool shock it takes to reach breakpoint depends on your pool gallons and combined chlorine level and a common problem is that today’s ever-popular vinyl lined pools cannot handle the required amount as they will damage and fade the liner over time. Painted pools can handle a great deal more but can fade and plastered pools can be blasted to no end. With fiberglass pools, you should be slightly more… conservative in your dosage.

HOW MUCH SHOCK? A good rule of thumb is to use one bag of shock per 10,000 gallons or 1 gallon of liquid chlorine. To be quite honest you have to “play” with the strength depending on your pool problem but a safe bet is to hit it with the 1 bag per 10K – plus 1 more bag, so you two-stepsget there without damaging your liner. So you take 3 steps forward and just 2 back. If that doesn’t do it, wait 1-3 days to make sure the level goes down and do it again. Now it’s 3 steps forward and 1 back. On the third shock you are 3 forward and 0 back.  Now you are done and regular chlorine tablets or any other sanitizing methods should keep it sanitized and clear!

Shock and chlorine will wear off faster with intense sun and less when the there is no sun. I always brush the pool floor and walls, then shock. Repeat until clear. Different levels of cloudiness demand different amounts of shock and I have come to know my pool and if it’s green with visible algae – I double the dose.

If the pool is very cloudy, way past hazy to milky – I increase the 1 bag of shock per 10K rule, and if it’s a weekly shocking, I do the 1 bag per 10K. My pool stays clear all summer long as long as I check it every day. That’s the secret. Just a quick glance before or after work and if it’s starting to turn, it’s time to brush & shock.

“I tried all that. What else is there?!?”

MILKY-POOL-WATERFILTRATION: Another potential scenario may be that your pool filter is not doing its job. The filter media could be worn, or water could be bypassing the filter media, and returning to the pool unfiltered.

SAND: If your sand is more than 5 years old, or has never been changed at all, then it should be changed. Old filter sand can sometimes clump and the water channels down the tank sides or between the clumps which causes poor filtration. You can also clean your sand each year with sand cleaner to rejuvenate it. This eliminates calcium build-up, oils, and organics that tend to cling to it. Fresh sand grains are square and edgy and when packed together, and effectively trap debris. But, as they are pounded by water they smooth out like rocks on a beach and lose their dirt trapping capability.

CARTRIDGE: If your filter cartridge is more than 3 seasons old it may be time for replacement filter cartridge. The membranes become clogged with oils, lotions, calcium, scale, and dirt. They lose their effectiveness as they become fuzzy, the straps break, the end caps get sticky, or they start to collapse. If you can afford it, buy a new one at the start of each season and use the old one for spring cleanup and then toss it out. Once a year, the pool inside of my pool store used to become cloudy beyond fixing with chemicals. Since I had a myriad of chemicals at my disposal, I tried them all! I would put in a new cartridge and voila! It would clear right up.

DE filters should also be monitored for performance issues.  DE grids or fingers should be cleaned with Filter Cleaner periodically, at least annually. Manifolds and pressure plates should be inspected for cracks where debris can slip back into the pool.  But for the most part a properly functioning DE filter will clear a pool quickly and keep it that way.

TURBID-POOL-WATERWHAT ELSE? But what is there to do if you have a successful cover removal, balanced the chemical properties properly, cleaned or replaced your filter, and yet the problem persists?

Turbidity is a fancy word for water that is not transparent because of stirred up sediment and also just so happens to mean confused, muddled, or disturbed ( which incidentally is just exactly how pool owners come to feel when dealing with cloudy pool water. Especially when they have a family and kids who want to use the pool, its 90 degrees out, and they can’t – for safety reasons.

CLARIFIERS:To effectively remove this sediment there is a method that is much less harsh than shocking. You simply apply a clarifier or super clarifier which is sold in quart, ½ or 1 gallon bottles and in a variety of brands. Clarifiers work best with sand filters and act as a coagulant to bond suspended particles together so they are bigger and more easily captured by your filter.

Clarifiers are also available in a gel, or gelatinous cube like Mira-clear which can be placed in your pump basket, erodes into your filter to fill the gaps in the sand, and trap fine particulates.

All of these clarifying agents are designed to clarify your water so it has that sparkling clear essence that allows us, as the saying goes, “to read the date on a dime” dropped on the pool bottom.

FILTER AIDS: And then there are some common filter aids like Synthetic DE, most often called Perlite or AquaPerl, which can be added to a cartridge filter by sprinkling a small amount into your skimmer, which effectively brings your cartridge down to a much smaller micron filter.

FLOCCULANTS: Another solution to try is a good pool flocculant. This phenomenal pool chemical is available as a liquid or powder that you apply directly to your pool and allow it to circulate, then turn your filtration system off and it weighs all of the sediment to the bottom of the pool so you can vacuum it up. It is best to vacuum it all to waste because the gummy residue will quickly clog up your filter, requiring frequent backwashing.

MILKY-POOL-WATERAND FINALLY there is a tip that people usually have a hard time believing. That is to use the pool!

Swimming and Splashing around gets that water circulated and into the skimmers and main drain better than anything else. Your pump and filter can only do so much to turn over all the of gallons in the pool mathematically in 8-10 hours, but does not necessarily turn over ALL of the actual water. Unless you are brushing daily, or have an automatic pool cleaner going, some water sits in stagnant zones and may not get filtered.

Sometimes it’s hard to get people in the pool when it’s cloudy but it will help. You just need to keep a sharp eye on all swimmers – and No Diving!

Once my pool is clean & clear I try to use it every day. This keeps it stirred up, ensures that I get a chance to inspect it, and I give it a quick test with test strips to make sure it is balanced.  So using the pool, daily inspection, and a once-a-week shock treatment are my secrets to clean and clear pool water.

So to recapitulate, and continue to curtail the cloudiness, remember it’s a combined effort of filtration, water balance, sanitation, circulation, frequent pool use and – maybe finding the right accessory chemical to help coagulate and trap suspended particles.

That is my step-by-step to remove cloudy pool water so you and your family can enjoy a sparkling clear pool!

Mike Cummings
InTheSwim Staff Blogger



Cloudy Pool Water Issues — 4 Comments

  1. The salt cholorinator stopped working. Cloudy Algae looking water. Water took down turn. Shocked then chorine nothing changed. Raised my alkalinity from 40 to 90 ppm with soda a. Raised ph to low end. Plenty chorine available. Still shows it needs soda ash some. Add more soda ash or give it a day or two. 26,000 ga pool approx

    • If you are still trying to kill, algae – the chlorine is much more effective at a 7.0 – 7.2 range. So, I’d probably keep it low until the water starts to clear. If the pool is still green, shock again, but keep adding it until the water turns a blue/grey color, and stays that way. If it still has a tinge of green, or if the chlorine level drops to zero after 8 hours, you need to add more shock, to make a complete kill or oxidation of the algae.

  2. Got one for you Mike…We had to drain most of pool this spring and do a lite repair, due to the cost of a refile or we had to use well water we decide to pump water out of the creek. The creek looks like ice tea ie: tannin colored, what if anything can be done to clear this water. I do have to add when you scoop out a class of water it looks clear…Thanks in advance Curtis

    • Hi, I’ve had a friend of mine fill his pool from the creek. I thought he was nuts, but it turned out OK. It was a little murky and tan colored at first, but he tested and balanced the pool water, and circulated a metal out product (sequestering agent) and some clarifier overnight, and then shocked the pool to a blue color the next day – no problems!

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