Pool Chemicals

Pool Water Chemistry Basics

Chlorine

Ideal Range: 2.0 - 4.0 ppm

Chlorine has been keeping pools clean and safe for swimmers worldwide for decades. Chlorine, in its many forms, kills bacteria viruses and prevents algae bloom. There are three types of chlorine liquid: tablets, granules, and liquid.

What to do if…

• Chlorine is too high. Stop adding chlorine and wait for the level to fall naturally.
• Chlorine is too low - Add Stabilized Chlorine or Pool Shock

Read - How To Choose A Pool Test Kit, Bad Pool Chemical Combinations

Cyanuric Acid - (Stabilizer)

Ideal Range: 30 - 50 ppm

Cyanuric acid is as important to chlorine as chlorine is to swimmers; it is commonly called chlorine’s sunscreen. Although chlorine is a powerful sanitizing agent, it is still relatively sensitive to the sun's UV rays, which can ‘burn off,’ reducing its effectiveness. The liquid and tablet forms of chlorine are called ‘stabilize chlorine’ because CYA is included in their formula. CYA’s inclusion into the chlorine formula ensures

Salt chlorine generators produce a pure form of chlorine, making it necessary to add CYA manually. Most chlorine pool shocks lack CYA, as well.

What to do if…

• Cyanuric Acid is too high - Drain portion of water, add fresh water
• Cyanuric Acid is too low - Add CYA

Read - Pool Cyanuric Acid Calculator, How To Break Chlorine Lock, The Relationship Between Chlorine and Cyanuric Acid

pH

Ideal Range: 7.2 - 7.6

By measuring your pool water’s pH, you’re measuring how acidic, neutral, or alkaline (base) your pool water is. On the pH scale, values from 0 to 7.0 are acidic, values 8.0 to 14 are alkaline, and the preferred neutral zone you want your water to be in is 7.1 to 7.9.

Was that measures on the acidic side of the scale can be corrosive and harmful to equipment and even to swimmers. Pool water on the base side of the scale can lead to scale and could build up deposits in plumbing or pool equipment.

What to do if…

• pH is too  high - Add pH Decreaser (Sodium Bisulfate)
• pHis too low - Add pH Increaser (Soda Ash)

Read -  Balancing The pH Levels In Your Pool, How To Lower pH Level In A Swimming Pool.

Alkalinity

Ideal Range: 80 - 120 ppm

Your pool water’s alkalinity measures its ability to resist changes in pH. A balanced pH prevents uncontrollable swings in your pool’s pH. If your pool is experiencing pH issues, it’s important to check the alkalinity before adjusting your pH.

What to do if…

• Alkalinity is too high - Add sodium bisulfate
• Alkalinity is too low - Add sodium hydrogen carbonate (baking soda)

Read - Why Does My Pool Water Burn My Eyes?

Calcium Hardness

Ideal Range: 200 - 400 ppm

Testing your water’s calcium hardness determines if your water is hard or soft. Water test results with a hardness of 400 ppm or higher are considered hard; this means there is too much metal in the solution. Hard water (400 ppm or higher) may have a metallic taste and could lead to scaling or iron stains. 

Soft water (199 ppm and below) may have a mild or neutral taste due to the absence of trace amounts of calcium and magnesium. Soft water may cause leaching, which is the process of the water extracting calcium, copper, and other metals from pool surfaces and equipment. A common sign of gunite pools affected by soft water is called etching;

What to do if…

• Hardness is too high - Drain a portion of your pool water and add fresh water.
• Hardness is too low - Add calcium hardness boosting agents.

Read - How to Balance Your Pool Water

Types of Pool Shock

Calcium Hypochlorite

Use: Boosting Chlorine Levels Without Increasing CYA

Commonly referred to as Cal-Hypo, it is the most common form of pool shock; your pool chemical kit is only complete with at least a bad or two of the stuff. Cal-Hypo contains chlorine and is available in different concentrations; we carry 68% and 73%, typical of the ranges you'll find.  It will boost your free chlorine level without increasing cyanuric acid levels.

Dichloro-s-Triazinetrione

Use: Preferred Shock for Vinyl Liner Pools, Does not Increase Calcium Hardness.

Di-chlor is recommended for vinyl liner pools as it dissolves rapidly and will not bleach or stain the liner.  It is also safer for fiberglass or painted surfaces for the same reason.

Potassium Monopersulfate (Non-Chlorine)

Use: Gets Rid of that “Chlorine Smell”

Non-chlorine shock is a powerful oxidizer that breaks down organic and inorganic materials like chloramines, body oils, and sunscreen. By breaking down the materials, traditional chlorine becomes more efficient in seeking and destroying bacteria.

Non-chlorine shock’s most noticeable effect on your pool is its ability to remove that “chlorine smell.”  That chlorine smell is caused by chloramines, which are expended chlorine. The acrid smell of chloramines is a sign that your pool is dirty, and its chemistry should be tested and rebalanced as soon as possible.