Guide to Basic Pool Chemistry
.Pool Chemistry is the backbone of owning and caring for your pool. In order to keep yourself and your loved ones safe, you’ve got to do a little studying, and a little homework in order to get things right. Don’t worry! We’re here to help!
First, let’s start with the basics. Bring your water in to your local pool supply store for a water test at least every 2 weeks! There, they will run a variety of tests for you, and they will give you recommendations of what chemicals and what dosages you will need to add in order to balance your water to keep it safe and sanitary.
Your local pool supply store will need a fresh water sample (less than 1 hour old, in a noncontaminated container) and they will need to know the gallonage of your pool. Don’t know the gallonage of your pool? Check out our FAQ page for more info on that!
Here are the usual tests that are performed…
Free Chlorine / FAC
1 – 4 ppm
Total Chlorine / TAC
*should match your FAC
pH (overall acidity of water)
7.2 – 7.8
80 – 120 ppm
200 – 400 ppm for chlorine pools
Cyanuric Acid / CYA
30 – 90 ppm for chlorine pools
*** as close to 0 as possible; otherwise, under 100 ppb ***
Total Dissolved Solids (TDS)
In a chlorine pool, you test for TDS,
In a salt pool, it should range from 2800 – 3400
Should be 0
Correct sequence of adding chemicals when making adjustments, if/when necessary:
- Calcium Hardness
- Cyanuric Acid
- Salt (*** ONLY IF IT IS A SALT POOL; OTHERWISE, GO TO STEP 7.)
- Phosphate Reducers & Enzyme blends
Alkalinity and pH:
Alkalinity controls your pH levels, and keeps them properly locked in place. Perfect Alkalinity is an 80.
Safe/neutral pH is a 7… anywhere between 7.2 to 7.8 is preferred. Perfect pH is a 7.4. Anything under 7 is considered unsafe.
Your Alkalinity Increasing and pH Increasing/Decreasing chemicals can be added within the same day, just not at the same time. Please allow 4-6 hrs. between both types of products for your pool to properly filter the chemicals. *** Remember, even if the water is clear, you should still allow a minimum of 4 hours for the Alkalinity to filter before adding any pH increasers/decreasing agents.
Pool Grade Alkalinity Increasers may be broadcast into the pool, preferably in front of returns that are located in your deep end, to help disperse chemicals more thoroughly.
You should always dilute any pH increasers or decreasing agents into a large bucket. We recommend filling a 5-gallon bucket ½ – ¾ full and adding your dry chemicals to the bucket slowly. Completely mix the dry chemicals and water with a wooden spoon or wooden stirrer until completely dissolved, leaving no lumps. Once everything is completely dissolved, slowly walk around the edges of the pool, adding the mixture to the pool water, taking care to add the majority in front of the returns, and avoiding the skimmers, to disperse the chemicals more thoroughly.
Disclaimer: It is safe to swim in your water 8 hours after any Alkalinity or pH changes
Calcium Hardness is often overlooked, but is a necessary addition. It “hardens the water” because soft water is generally classified as corrosive.
It will not do any damage to you, so please do not panic, but in order to protect your plumbing, liner, and equipment throughout the season (since they are all under pressure with water constantly flowing through them), you will want your Calcium Hardness level to be a minimum of 200, with 300ppm being ideal.
*** Always add your Calcium Hardness agent a minimum of 24 hours after Alkalinity and pH products. Failing to do so might cloud your pool water excessively. ***
Calcium Hardness increasers usually generate heat when coming in contact with water, so please exercise caution when adding these chemicals to the water’s surface. It should always be broadcast into the pool slowly and never prediluted!!! Always follow the directions on the packaging, and never exceed chemical dosages from packaging so as to protect your liner, and so as to not over cloud your pool water.
Disclaimer: It is safe to swim in your water 8 hours after any Calcium Hardness increases.
Many brands offer liquid and a pelleted versions of Cyanuric Acid – otherwise known as CyA, Stabilizer, or Conditioner – all of which act as a “sunblock” for your chlorine, keeping it working and active. The ideal range for a chlorine pool is 30-90ppm, with 90ppm being on the high side.
Please remember that chlorine tabs often contain stabilizer which will add to this count throughout the season. For a salt pool, liquid CYA is safest for the salt cell and should be between 60 and 80 ppm to ensure your salt cell is not over working itself.
Cyanuric Acid should always be added a minimum of 24 hours after any Calcium Hardness products, with 48 hours being ideal, to ensure they do not cloud the water and work most efficiently. Though you will see that the pelleted version of Cyanuric acid may be more cost friendly than the premixed liquid, if you own a salt system, please do not risk it! The pelleted chemicals often times do not dissolve completely and can find themselves scaling prematurely, causing issues later on.
The pelleted or granular version of Cyanuric acid must be made into a slurry before being added to the skimmer. We recommend wearing goggles, and gloves, and using a skimmer sock, as well as a wooden spoon or stirrer, and a 5-gallon bucket. Follow the chemical dosing from the back of the packaging, and create a slurry using warm water. You may have to stir this mixture for upwards of one (1) hour before it is ready. Once you achieve a mainly liquid texture, you can then slowly, and carefully, pour the mixture into the skimmer that has been equipped with the skimmer sock.
Or, the easier and more recommended route would be to use the prediluted liquid Cyanuric acid. After obtaining a water test, and calculating how much you will need based on your gallonage, follow the directions on the packaging. Most packaging states you will need to shake the gallon for approximately one minute, then slowly add ½ gallon to the pool skimmer, while slowly walking around the edge of the pool and adding the rest of the gallon. Once the gallon is empty, fill the empty gallon with pool water, shake again, and empty out the contents to ensure you got all the product.
Disclaimer: It is safe to swim in your water 8 hours after any cyanuric acid increases
Phosphate Reducers and Enzyme Blends
Phosphates are organic compounds derived from phosphoric acid. They are present in a multitude of things, ranging from environmental attributes: leaves, pollen, grass, flowers, dirt, sand, rain water; to human based attributes: hair cells, skin cells, urine, fecal matter, hair products, detergents, sunblock, etc. Essentially, they are a food source for algae. They will not do you any harm, and you cannot even see them, however, it is essential to your pool that you remove them as much as you can. The best way to do this is through the use of enzyme blends.
For more information on Phosphate reducers and Enzyme blends visit our FAQ page!
Disclaimers: Any Phosphate Reducers or Enzyme blends should be added a minimum of 72 hours after any Cyanuric acid to ensure the live enzymes have the best chance to thrive. IT IS NOT RECOMMENDED TO SWIM FOR 24 HOURS AFTER ADDING LIVE ENZYMES TO POOL WATER.
ALWAYS FOLLOW THE DIRECTIONS ON THE CHEMICAL PACKAGING, AND NEVER USE ANY CHEMICALS THAT MAY HAVE GOTTEN WET OR DAMAGED IN TRANSPORT!!!
It is very important to maintain proper water chemistry to protect not only your pool equipment, but your liner, your concrete, your handrails, and yourselves!