Water Chemistry
CHEMISTRY is keeping the water clean by maintaining pH, Alkalinity, Chlorine and Stabilizer. When these levels are in good range, it is balanced. When even one of these levels are off, your pool chemistry is off and will cause problems algae, cloudy water, and unsanitary conditions. They are all important because they all effect each other.
It seems so easy when you are cooking; you add more liquid when it’s too thick, add salt for more taste. Sadly, pool water chemistry is not as simple.
The reason it is more complex is that the levels (chlorine, pH, alkalinity, stabilizer) all effect each other directly or indirectly.
CHEMISTRY refers to Adding chemicals, Adjusting levels, Common Water Problems (cloudiness/algae),
Adding chlorine, Too many Chemicals, Using the Correct amount and more.
Chemistry Basics
Pool Chemistry is keeping the water clean by maintaining pH, Alkalinity, Chlorine and Stabilizer.
When these levels are in good range, it is balanced. When these are too high or too low,
your pool is more likely to to get cloudy water, algae growth, or unsanitary conditions because
the chlorine can’t clean. pH and alkalinity have a direct effect on each other.
When Alkalinity goes up, pH goes up. This is why you want to adjust alkalinity FIRST.
pH
WHAT IS IT: How acidic the water is (0 = acidic, 14 = no acidity)
WHAT DOES IT DO: Keeps Chlorine effective as a sanitizer
Tablets and Granules have a low pH and will lower pH level.
Liquid Chlorine has a higher pH and can gradually push pH higher.
LOW pH: Chlorine becomes less stable and will be used faster, which means $$ for more chlorine.
Water can be corrosive, itchy skin, watery eyes.
HIGH pH: Chlorine can’t work. Unsanitary water, Algae can bloom
Chlorine works best at a lower pH so when it gets too high, chlorine isn’t as effective or isn’t working at all.
Alkalinity
WHAT IS IT: Measurement of how well the water can resistance to change in pH level.
WHAT DOES IT DO: Helps to prevent pH from going up or down
LOW ALKALINITY:
pH level can swing up & down
Chlorine will not be effective
Corrosion of anything metal (ladders, frame, etc)
HIGH ALKALINITY:
pH bounce up to a level where chlorine will not work
Cloudy pool water
Because pH levels are affected by Alkalinity, it is a challenge to lower Alkalinity without lowering pH
CYA (Stabalizer)
STABILIZER
Also called CYA or Cyanuric Acid or Conditioner
WHAT IS IT: Chemical that protects Chlorine from being burned off by the Sun’s UV rays.
WHAT DOES IT DO: Sunscreen for Chlorine.
LOW STABILIZER: Chlorine breaks down faster requiring more Chlorine more often
HIGH STABILIZER: Can result in chlorine lock, which means Chlorine can’t work no matter how much is in the water (opinions vary on this)
Calcium/Hardness and metals in water are so common, they are worth mentioning. Calcium is not as much an issue in aboveground pools, so focus on Alkalinity, pH, Stabilizer & Chlorine. Metals are worth mentioning because depending on where your water comes from, it can turn green or brown very fast if you have iron in the water.
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CALCIUM / HARDNESS
Calcium refers to calcium in water, while HARDNESS refers to how much Calcium AND Magnesium is in the water.
WHAT IS IT: How much calcium & magnesium in the water. A way to measure hardness in water.
WHAT DOES IT DO: Not as important in aboveground Pools
LOW CALCIUM: Erosion in plaster pools
HIGH CALCIUM: Murky water, Calcium deposits can stain/scale liner
METALS
WHAT IS IT: Naturally occurring minerals in water, most common, Copper, Iron and Manganese
WHAT DOES IT DO: Stains liner, discolors water, can interact with pool chemicals
HIGH METALS: Iron causes green/brown water, Manganese causes Black/purple staining
Chlorine, Water and Oxygen all oxidize iron; when iron oxidizes, it turns to iron oxide (RUST)
TESTING
LEVELS - BALANCE - CHEMISTRY - NUMBERS - TEST - RESULTS are some common terms used to describe what the chemical amounts are in the pool.
There are multiple options you can use to test the pool water.
Take water Sample to a Pool Store
Testing Kits
Test Strips
Or some may choose to have it done professionally.
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When you are just starting and taking in all of the information about pools, and trying to understand what each of the chemical levels are, take the easiest method; test strips. Matching colors on a strip is easier than adding drops and trying to determine what shade of which level you are looking at.
Brand of test strips are not as important as what is on the strip. Look for a 7-way test strip that measures:
Hardness
Free Chlorine
Total Chlorine
pH
Alkalinity
Stabilizer/CYA
If you have a salt water generator, your test strips will be different because SWG needs to measure salt.
Test Strips measure several levels in one strip that you dip into the water. Each individual strip can only be used one time.
