Basic Pool Chemistry 101

Practicing proper pool chemistry is important and easy. In this guide, we will provide you with everything you need to know to keep your pool clean and clear.


There are 2 basic elements to pool chemistry: water balance and sanitation.



Your pool water is delicate, and in order to reach perfect pool harmony, it must be balanced.

Balancing your pool means keeping the pH of the water between 7.4 and 7.6, which is slightly above neutral on the pH scale.




There are 3 main ingredients to keeping this balanced: pH, alkalinity and calcium hardness.



pool-phProper pH Level: 7.4 to 7.6

pH alone is unstable. Rainwater, swimmers, and just about anything that enters the water can affect the pH level. When pH is low, it means your water is acidic, and when it’s high, you water is basic.

To give you an idea of how pH works, our tears are pH neutral. If they had a low pH, it would burn when we cried. And if the pH was high, it would dry out our eyes.

Always keep a good supply of pH Increaser on hand because this reading can change frequently.












pool-alkalinityProper Alkalinity Level: 100 to 150 ppm

Alkalinity is a pH buffer, meaning it helps to keep the pH from drastically moving up and down the pH scale by absorbing major changes to the waters before affecting the pH.

It’s also a good idea to keep a hefty supply of alkalinity increaser on hand since this reading can fluctuate.












calcium-hardness-rangeProper Calcium Hardness Level: 175 to 225 ppm and 200 to 275 ppm for plaster pools

Without calcium, your water will become hungry for it and seek to fulfill it’s appetite by feasting on your pool’s plaster, and anywhere else it can get it.

Adding calcium hardness to your water will help protect your pool walls and equipment in the long run. However, too much calcium can cause scaling and other issues.












[NOTE: Calcium hardness should only be added once in the beginning of the season. Keep an eye on it throughout the year to make sure it stays within range. If the calcium in your water is high, you will have to dilute the water by draining it a tad and refill with fresh water.]



It’s important to keep your eye on your pH and alkalinity levels – at least once a week – by using a home test kit or test strips.












To keep your pool balanced, you need to keep these chemicals on hand:

You’ll notice I didn’t mention alkalinity decreaser. Most major pool chemical companies do not produce it and here’s why…

If your pH and alkalinity are low, alkalinity increaser will raise both. You may need to add a little pH increaser if the pH doesn’t reach 7.4 – like fine tuning an instrument.

If your pH and alkalinity are both high, pH decreaser will lower both.

If just your alkalinity is high, your pH will also be high and you can use pH decreaser.

If your pool is properly balanced at all times, it will make your pool’s sanitizer work more effectively – especially chlorine.




The most common form of pool sanitizer is chlorine, but there are others you can use, including:

  • Bromine: chlorine’s halogen cousin
  • Biguanide: Baquacil or SoftSwim
  • Minerals: silver and copper



Proper Chlorine Level: 1 to 3 ppm

Chlorine is an extremely effective bacteria and algae killer, and cost effective.chlorine-tablets

There are a few ways you can introduce chlorine into the pool water, including:




This is a chlorine alternative. It’s an effective sanitizer for swimming pools and even makes the water feel smoother.

These chemical packages are more expensive than traditional chlorine-compatible chemicals, and they come in granular/powder form.













Proper Chlorine Level: 0.5 ppm

Silver and copper minerals are introduced to the water by an mineral system that resembles a chlorinator. These minerals work to sanitize the water, but they are much slower than chlorine.

A mineral system is NOT a complete chlorine alternative as chlorine is still required – but only a small amount as backup.











Shocking your pool is another term for oxidation.

When a chlorine particle attacks and kills bacteria, or other organic material in your water, it forms a chloramine, which is chlorine that doesn’t kill anymore. This particle just floats around in your water until it can be oxidized and broken apart.

In order to oxidize these chloramines, you must “shock” the water by adding enough chlorine – or non-chlorine shock including Potassium Monopersulfate – to reach breakpoint oxidation.











What is Breakpoint Oxidation?

To reach breakpoint oxidation, the chlorine reading must be 10 ppm over your combined chlorine reading.

Your chlorine has two readings: free chlorine (FC) and combined chlorine (CC). Free chlorine refers to the chlorine that is free and available to kill.

NOTE: Pool shock products are made with unstabilized chlorine or no chlorine at all. They will go in, do their job, and get eaten up by the sun’s UV rays very fast. That’s why it’s important to shock your pool at night or dusk, and let it work for 8 hours (with the pool running) throughout the night.













If you only used pH, alkalinity, calcium, and a sanitizer, you could keep a clean and healthy pool all year long. However, there are a few more products you should be familiar with in case you need or decide to use them.


Cyanuric Acid (Water Stabilizer)

Most chlorine products you add to the water will be stabilized chlorine. However, if you start with fresh water, you might want to add some cyanuric acid (aka water stabilizer) as a stabilizer base so that the chlorine doesn’t get burned off by the sun’s UV rays so quickly. This chemical will protect your chlorine from the sun.



Algaecide is a algae preventative. There are certain algaecides on the market that claim to kill algae, but the best killer is chlorine.

Use algaecide as a backup. If your chlorine levels dip down, and you don’t catch it in time, the algaecide will keep the algae at bay until you can get the chlorine back up.

If you’re currently having an algae problem in your pool, algaecide may not be your best option. Thankfully, we have a solution to help you get rid of algae and keep it from coming back in the following article:





Clarifier and Floc

A water clarifier helps by bringing all those tiny particles that are making your water cloudy and combining them into bigger particles that your filter will have a better chance of filtering out.

Floc or Flocculant, grabs those tiny particles, brings them together, and sinks them to the bottom. With pool floc, you will have to manually get those particles out of your water by vacuuming to waste.





Stain and Scale Remover

If you have metals in your water, like copper and iron, you can use a metal remover or stain and scale remover to keep those metals in solution so that your filter can filter them out.

If metals come out of solution that can attach themselves to the walls and other parts of your pool and produce unsightly stains.







To maintain a safe and healthy swimming pool, you need to keep your pool chemicals at the following levels:

  • pH: 7.4 to 7.6
  • Alkalinity: 100 to 150 ppm
  • Calcium Hardness: 175 to 225 ppm and 225 to 275 ppm for plaster pools
  • For Chlorine or Salt Water Pools: 1 to 3 ppm (I recommend you keep it at 3 ppm)
  • For Bromine Pools: 3 to 5 ppm
  • For Biguanide Pools: 30 to 50 ppm
  • For Mineral System Pools: 0.5 ppm of chlorine

Make sure to practice good pool circulation and filtering, and keep your pool cleaned by vacuuming and skimming frequently.

My 3 Cs of pool care include: cleaning, circulation and chemicals.

Happy Swimming!

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