Swimming Pool pH level Why It Is Important

The pH level of a swimming pool; what is this really? It is actually the measure of how acidic or how basic the water is in your swimming pools. The level of the pH balance for a swimming pool is very essential to its overall water chemistry. Therefore it is vitally important that you learn how to test and adjust it.

This pool balancing factor is one of the most important element in swimming pool water chemistry.

The truth of the matter, is that it affects every other element in the pool chemical balancing of your swimming pool or spa water.

The pH levels for swimming pools are measured on a pH scale that ranges from 0 to 14.

Where a reading of 0 indicates an extremely strong acid base (acidic water) and a reading of 14 means a very strong base (basic water). A pH level reading of 7 which is at the middle of the scale, means that the water is very neutral. This in fact is the neutral point for water. The most desirable pH level for a swimming pool or spa is between 7.2 and 7.6.

This range will keep your swimming pools and spas slightly alkaline and it is the most comfortable range for the eyes of your human swimmers. The truth of the matter is that these ranges will also provide optimum use of the free chlorine content in your pools; thus giving your swimming pool optimum sanitation.

This will also help in maintaining your pool water chemistry, so that it does not become corrosive or scale forming.

What Happens When Your pH level Is Too Low?

Whenever the pH level of your swimming pool or spa drops too low, the water will become very acidic. When this happens, the water tends to corrode or etch anything that it comes in contact with. Generally, water that is acidic will be under-saturated or very hungry. This means that it will seek out something to dissolve and combine with.

Problems caused by low pH levels include...

  • Acidic swimming pool and spa water.
  • Chlorine residuals dissipate very quickly.
  • Eye irritations of your bathers occur.
  • Etching of your pool plaster and wall surfaces occur.
  • Corrosion of the metal parts in your mechanical system occurs. This includes the impellers of swimming pumps, spa pumps, and the elements of your swimming pool heater cores.
  • Staining of the walls in your swimming pools and spas.
  • Rapid loss of your pool alkalinity levels.

Problems caused by a pH level that is too high include...

  • The activity of your pool chlorine level is slow and inefficient.
  • Scaling and discoloration of the walls in your swimming pool or spa occurs.
  • Cloudy water in your  swimming facility.
  • Your swimming pool filters will work harder than normal.
  • Eye irritations will occur among your swimmers.

There are many factors that can affect the level of your swimming pool's or spa's pH. Some of these influencing factors include...

  • The human waste of your swimmers.
  • Your swimming pool or spa disinfectants.
  • The make-up or source water that is use for your pool.
  • Air-borne debris.
  • Aeration water around your pool deck.
  • Evaporation.

Controlling The pH of Your Swimming Pool

This process is extremely important for several reasons. Firstly, it provides comfort to your bathers (zero eye burns or irritations). Secondly, the efficiency of your pool sanitizer is kept constant. Thirdly, you will be providing protection to the mechanical parts in your recreational water facility.

Therefore, you need to understand the best ways to control and maintain it.

However, before you make any attempts to adjust your pH, you should firstly test and if necessary, adjust your total alkalinity levels. Your pH level is easily controlled if you maintain a proper level of total alkalinity. Often times, when your alkalinity levels are correct, your pH levels will be correct also.

How To Adjust The pH Level In Your Swimming Pool

Now for you to avoid any of the problems that I have listed above, you must maintain your pH levels between 7.2 and 7.8. However the most desirable level for pools and spas is between 7.4 and 7.6. Meanwhile, if the level of your pH is too low, you should run an alkali demand test.

This test, when done correctly, will let you know how much Soda Ash (sodium bicarbonate) you will have to add.

Never add more than 2 lbs of soda ash for every 10,000 gallons of water in a single treatment process.

Make sure that your swimming pool pumps are running before adding any type of chemicals to your pool.

Once you have allowed your pool water to properly filter out and re-circulate, retest once again. This will let you know if you have to carry out any further treatment. Caustic Soda is another swimming pool chemical that is used to raise the pH in pools and spas.

This chemical is sometimes added to swimming pools by means of a chemical feeder pump that is controlled automatically.

If your pH remains low, you may have to raise your total alkalinity in order to stabilize them. The table below gives you a pretty good idea on how to go about raising your pH levels in your pool or spa.

How To Raise Your pH Level With Soda Ash

Swimming Pool Volume
7.2-7.42/3 oz.3 oz.6 oz.9 oz.12 oz.1 lb.2 lbs.
7.0-7.23/4 oz.4 oz.8 oz.12 oz.1 lb.1 1/4 lbs.2 1/2 lbs.
6.6-7.01 1/4 oz.6 oz.12 oz.1 lb.1 1/2 lbs.2 lbs.4 lbs.
Under 6.71 1/2 oz.8 oz.1 lb.1 1/2 lbs.2 lbs.2 1/2lbs5lbs

How To Lower Your pH Level With Muriatic Acid

Now if your pH level is too high, you will need to carry out an acid demand test to determine the amount of muriatic acid that has to added. Adding muriatic (Hydrochloric acid) to your swimming pool lowers its pH level. Something to remember! Muriatic acid not only lowers your pH levels, it also lowers your alkalinity levels as well.

So be sure to check you total alkalinity after all treatment. Now you can use an acid salt such as Sodium Bisulfate which will lower your pH as well. Best practice here - is to add the acid to the deep end of your swimming pool carefully.

Be sure to avoid pouring it near the wall of your pool or near any of its fittings. Special precautionary measure here: When you are using or diluting acids, always, always, add the acid to the water. Never add the water to the acid. The table below, can be use as a guide on how to go about lowering the pH level in your swimming pool.

You would use this table, after you have determined that the level of your pool's pH needs to be lowered. A pH level testing is required first.

How To Lower pH Levels With Muriatic Acid

Swimming Pool Volume
7.6-7.81 1/4 oz.6 oz.12 oz.18 oz.24 oz.1 qt.2 qts.
7.8-8.01 1/2 oz.8 oz.16 oz.24 oz.1 qt.1 1/4 qts.2 1/2 qts.
8.0-8.42 1/2 oz.12 oz.24 oz.1 1/4 qts.1 1/2 qts.2 qts.1 gal.
Over 8.43 oz.16 oz.1 qt.1 1/4 qts.2 qts.2 1/2 qts.1 1/4 gal.

Maintaining the pH level in a swimming pool or spa is never easy. There are several factors that directly affect the level of the pH of your swimming pool. They include...

  • Acid.

  • Gas chlorine
  • Trichlor chlorine.
  • Dichlor chlorine.
  • Rain water.
  • Alum.
  • Organic litter.
  • Make or source water.

On the other hand, there are factors that directly affect your pH level by raising it. These include...

  • Soda Ash.
  • Sodium hypochlorite.
  • Calcium hypochlorite.
  • Caustic soda.
  • Bicarbonate of soda.
  • Swimmers waste.
  • Algae growth.
  • Your make up water.

Remember when using any form of spa or pool care chemicals, there should be no swimmers present in the water. Your swimming pool should also remain closed until, the pool chemicals are completely dissolved and dispersed in the water.

This include all pool chemicals that are used to raise or lower your swimming pool pH level.

A low pH level will change your total alkalinity

Swimming pool care home page

Spa Chemicals - Save Up 25% off Retail at Hot Tub Works! Shop Now!

Back To Top

New! Comments

Have your say about what you just read! Leave me a comment in the box below.
Share this page:
If you enjoy this page? Please pay it forward. Here's how...

Would you prefer to share this page with others by linking to it?

  1. Click on the HTML link code below.
  2. Copy and paste it, adding a note of your own, into your blog, a Web page, forums, a blog comment, your Facebook account, or anywhere that someone would find this page valuable.