What Chemicals are Needed for Pools?

chemicalsKeeping your swimming pool clean and clear can be a tough job, especially if you don’t have the right chemicals. Keep the basics on hand for regular maintenance as well as anticipated water problems.

My little blog post today lists below all of the pool chemicals that every pool owner should be familiar with; at the end is a short list of pool chemicals that should be kept in stock.


CHLORINE-TABLETSThese are the chemicals that you use to keep water sanitized and disinfected. There should be a constant level of chlorine (or bromine) in the water at all times, without a lot of peaks and valleys.

TriChlor: 3” tabs, or 1” tabs or sticks. With cyanuric acid. Add them to a chlorine floater or a installed chlorinator.

DiChlor: granular. With cyanuric acid. Powdered form acts quickly to chlorinate pools, fountains or spas.

Bromine: 1” tabs. Great for spas; works better in hot water, and can be regenerated by shocking. More pH stable as well.

Cyanuric Acid: Liquid or dry chlorine stabilizer. Protects chlorine from damage by UV rays. Small amounts are added to dichlor and trichlor; add extra if pool was drained, to maintain 30-50 ppm. Drain some water and refill if CYA levels get much higher than 50 ppm.


pool-shocksOxidizers are the secondary sanitizer, used every few weeks to kill algae and bacteria. Chlorine or Non-Chlorine shocks are in a powdered form, just open the bag and pour it into the pool.

Calcium  Hypochlorite: Cal Hypo pool shock is used to quickly sanitize pool water, boost chlorine levels and kill algae. Works best with a low pH level of around 7.2.

Chlorine Free Shock: Granular potassium monopersulfate (non- chlorine). A fast acting oxygen based sanitizer that burns clean with no residue, and you can swim right after treatment.

Lithium Shock: Lithium hypochlorite. This one is great for pools with liners because it won’t bleach the liner, and also dissolves right away so is safe to swim right after treatment.

Water Balancers:

pool-chemicals-water-balancersTo keep your water in balance, you should test the pool several times per week for chlorine and pH levels, and adjust as needed. Test total alkalinity every few weeks or if you have pH troubles, and test calcium hardness and cyanuric acid levels every month.

pH Increaser: Granular Soda Ash. Increase pH when levels fall below 7.2 ppm. 1 lb of pH Up will raise pH about 1-click, from 7.2 to 7.3 for example, in 10000 gals of pool water.

pH Reducer: Granular Sodium Bisulfate, or Dry Acid. Reduce pH when levels rise above 7.6 ppm. Also used to lower total alkalinity.
1 lb pH Down will lower pH about 3-clicks, from 7.8 to 7.5 for example, in 10000 gals of pool water.

Alkalinity Increaser: Granular Sodium Bicarbonate. Raise total alkalinity when levels fall below 80 ppm. 1 lb of Alkalinity Increaser will raise TA by about 10 ppm, in 10000 gals of pool water.

Calcium Hardness Increaser: Granular Calcium Chloride. Raise Calcium hardness when levels fall below 150 ppm. 1 lb of Calcium Increaser will raise CH by about 10 ppm, in 10000 gals of pool water.

Chlorine Neutralizer: Granular Sodium Thiosulfate. Use if chlorine concentration becomes too high. 1 lb of Thiosulfate will lower free chlorine levels by about 10 ppm, in 10000 gals of pool water.

Chemical Combo Packs: Pool Chemical packages you can choose from that include the tablets, shock, algaecide, and stain away you’ll need to carry you through your entire pool season. These are a great way to get yourself started with the bare essentials.

Specialty Chemicals:

specialty-chemicalsThere are many specialty chemicals that can come in handy when unexpected problems arise, or to keep your pool looking it’s best. This is one of the largest categories of pool chemicals, for every possible pool problem!

Algaecides: Some are copper based, most are non-metallic polymers. Helps to prevent algae from growing in your pool – use pool shock to kill algae, and algaecides to keep it from returning.

Clarifiers: Clarifiers coagulate tiny particles into bigger particles that can be trapped in the pool filter. Flocculants attract particles into heavy clumps that sink to the floor for vacuuming to waste.

Enzymes: Enzymes like Pool Perfect break down oils and other forms of non-living organic contamination from the water, removing scum, oils and odors.

Filter Cleaners: Used to clean sand, D.E., and cartridge filter elements to keep your filter working well. Removes oils, minerals, metals and other filter clogging gunk.

Metal Magnets: Sequestering agents are used to lock-up trace metals from the water and keep them in solution, so they don’t stain your pool surfaces.

Phosphate Removers: Products like PhosFree break down phosphates in the water. Phosphates are the primary food source for algae. Without food, algae can’t survive.

Stain Removers: Prevents or removes surface stains, scaling, and colored water due to minerals and metals in the water. We have over 15 different pool stain chemicals.

Tile & Vinyl Cleaner: Works great to help remove oils and grease build up around the water line, or on furniture, skimmers, diving boards and slides. Pool Cleaner won’t affect pool chemistry.

Start Up Kits and Closing Kits: When it comes to opening and closing the pool, or stocking up for the season, check out our chemical value packs that contains everything you need!

What Chemicals Should be Kept On-Hand?

As a minimum, the average pool will want to keep the following chemicals on hand – even if you use a salt chlorinator, you will need these other pool chemicals from time to time:pool chemical kits

  • Chlorine tablets and pool shock
  • Pool pH Up and/or pH Down
  • Test strips or test kit

Every pool will also need other chemicals to raise calcium, cyanuric or alkalinity levels, usually once per year – and clarifiers, enzymes, algaecides can be an important part of the overall routine, or are especially handy when you’re in a pinch!

12-categories-of-pool-chemicalsThere’s lots to learn, with 12 categories of pool chemicals – you won’t need them all; but it’s important to understand what they do, so that when you do need them, you know which chemical to use!

Safe swimming!





Christine Silvestri
InTheSwim Staff Blogger




What Chemicals are Needed for Pools? — 12 Comments

  1. Hello so I bought a intex 12′ by 36 pool and I’m so confused on what chemicals to use I have 3-1inch chlorine tablets in the filter but I’m not sure how much of the shock to put in the pool seeing as though the pool is small and says it hold 1,485 gallons. I also have he non chlorine oxidizer which says to put 1lb for every 10,000 gallons how much of that should I put ? Or should I buy the chlorine shock instead ? I Want to make sure the water is sanitized and safe to go into the pool.

    • Hi, you need a test kit, if you dont’ have one already. Use enough tablets to create a consistent and constant 1-2 ppm of chlorine in the water. Your test kit will tell you if you are using too many or not enough tablets. For the shock, either is OK (non-chlor or chlorine, but chlorine is best for algae killing, but both are suitable for bacteria and chloramine oxidation). Since it’s 1 lbs to 10K gallons, you only need about 1/5 of a pound, unless water conditions are bad, then maybe 1/2 lb, or if really bad – perhaps the whole bag. If using less, be sure to seal the bag very tightly, clamping with several paperclips, and keeping in a cool, dry place with no chance of spilling or contamination. Also important for overall water health is your pH level, Test every few days and adjust as needed, with pH up/ ph down chemicals, to keep the pH around 7.2-7.6. If you have trouble with this, check the total alkalinity level, it may be too high or too low.

  2. Ms. Silvestri, I have an above ground 10,000 gallon pool what do you recommend as far what chemicals and their quantities I should use. Thank you for your help

    • Hi Leon, Every pool has its own chemical needs, but there are some shared chemicals that all pools need.
      1. Chlorine Tablets, 3″ size, used in a chlorine floater. Use enough tablets (2-3 depending on water temp), to maintain a constant 1-3 ppm chlorine, confirmed by regular testing. Probably need 25 lbs per season
      2. Chlorine Shock, 1 lb granular Cal Hypo. Use 1-2 bags, added by first pouring the bags into a 5 gal bucket of water and stirring to dissolve, then pour around pool. Used to kill visible algae, or to remove combined chlorine, kill bacteria missed by the tablets. Also useful if you run out of tablets and forget to refill the floater, add 1 bag (pre-dissolved to protect the liner) to raise chlorine level fast, then refill the floater and it will catch up. Probably need 12 bags per season.
      3. pH increaser, Soda Ash. Use to raise the pH level if it gets too low. Probably need 10 lbs per season. Keep pH at 7.2-7.6
      4. pH decreaser, Sodium Bisulfate. Use to lower the pH level and the Alkalinity level. Probably need 10 lbs per season. Keep Alkalinity at 80-120 ppm
      5. Cyanuric Acid, Stabilizer or Conditioner. Use to protect the chlorine from the sun. Need 2-3 lbs to raise cya level to 20-30 ppm, per 10000 gals.
      Depending on your initial water tests, you may also need alkalinity increaser (minimum Alkalinity is 80 ppm) and some Calcium Hardness increaser (minimum Calcium level is 150 ppm)

      You’ll also need a reliable test kit or test strips to test the chlorine and pH levels 2-3x per week, Alkalinity and Calcium Hardness 1-2x per month.

      Those are the basics. Some people find that they need to use an algaecide to assist the chlorine in keeping algae under control, and some may need some help from clarifiers to help a small pool filter perform better.

    • Hi Alan, you will need to maintain a constant and consistent chlorine level, and a good pH level. Chlorine can be added with a floating chlorinator, and a few chlorine tablets. when they dissolve, add two more. Because your pool filter probably is small and not so effective, I would also recommend using a weekly addition of pool algaecide and clarifier, following label dosage.

  3. Hello Ms.Silvestri, I purchased a Bestway 12′ x 36″ Fast Set Inflatable Above Ground Pool w/ Filter Pump and have not a clue what kind of chemicals to use to treat the pool. The pool holds 2200 gallons of water and is all rubber. Please help?

    • Hi Robert, you can use a chlorine floater with 1-2 chlorine tablets per week to keep the chlorine level up. You will also want to test the pH level regularly, with test strips, and may need to use pH up or pH down to adjust the level. A bottle of Algaecide 60+ would also be advised, to help your chlorine keep the water clear. Also, you can use liquid bleach (unscented) to raise the chlorine level higher, add 2 cups of bleach per week, in the evening, to kill anything that the tablets did not kill.

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