pH of swimming pool water

water PH test kit

Poor pH balance causes nearly every type of stain that our technical team see each day and also makes the water unsafe for swimming. Our photo gallery shows some extreme cases where the pH has been left to drift a long way from the suggested level. This pH increase causes stain producing minerals, metals, copper, calcium or manganese to bond to the surface of the pool interior leaving an unsightly stain that will not brush away. Thankfully, these stain issues can be rectified through our stain treatment process.

We often tell our customers that if everyone kept their pool water pH safely balanced they would love their pool again and spend a lot less money at the pool shop.

Take a water sample to your pool store that is already pH balanced.  You’ll find that you save a lot of money on chemicals because the ‘foundation’ of your water chemistry is balanced. You may often find that you don’t need to buy so many expensive chemicals!

What is the right pH level for a swimming pool?

Maintaining the correct pH level of (7.4) in your swimming pool is one of the most important components of water chemistry.  If every pool owner did this regularly, we would go out of business!  This is because very few people would ever have staining in their pool.

If your pH is too low, it means that your water is aggressive (or acidic) and that it will want to dissolve any materials that it can to try and re-balance itself.  This may include, the cement in your pool interior, tile grouting and even the copper piping in your solar or heat pump.

On the other hand, water that is very high in pH will try to re-balance itself by depositing (or precipitating) calcium, metals and minerals onto the surface of the pool or pipework. The result is a rough pool surface, calcium spots, mineral staining and sore eyes for swimmers. In most cases, chlorine levels have nothing to do with red eyes after swimming.

Remember that the pH scale is logarithmic so that it’s simple to use.  This means that small changes in the numbers are actually HUGE changes in practice.  For example, lemon juice has a pH of 2 and humans can drink it without a problem.  However, hydrochloric acid is just a little lower on the scale at 0 but drinking this could be fatal.  This is because hydrochloric acid is actually 100 times more acidic than lemon juice.  Such a massive change in acidity just 2 digits down the (0 -14) scale!

Remember, pool water is either dissolving minerals or dumping them on the pool surface.  The only way to avoid this is to keep the water pH properly balanced. When the pH is in balance it does not add to or take away from the surface.  It is in balance.

How to test pool water

We suggest using a simple (drops) water testing kit to measure your pH each week. Testing the water yourself is the best and often the most convenient way for pool owners to keep their water balanced. It takes less than 15 seconds to do and may mean that you don’t have to visit the pool store as often. Many of our customers have been very grateful for giving them this advice. The reagents in these kits are used in some of the most sophisticated testing equipment used in pool shops today. When tested properly, the results from this test kit are very accurate. Maintaining the correct pH is one of the best things you can do to keep your pool water clear. Best of all, it may also save you a heap of money on pool chemicals at the pool store.