Easy Guide to Testing Your Pool Water
While swimming pools are fun, they need care if you want them to stay clear and safe for swimmers. Testing and balancing the water content in your pool is not only crucial to maintaining its finish and filtration system, if the water chemicals are out of whack it can be harmful to skin and eyes.
The following guide will explain the right way to test your pool water without much fuss.
Testing Chlorine Levels
The main swimming pool chemical used by most to free their pool of bacteria is chlorine. It’s important to make sure the levels of chlorine are optimal by using a pool test kit that can be bought at any pool store, many DIY outlets or online.
You’ll want to dip the plastic tester into your pool at a depth of at least 18 inches and make sure the sample water reaches the “fill” line for an accurate “catch”. Test kits vary, but the general step is to add five drops of the first solution which will be a chlorine indicator. Then close the caps on the vials and slowly invert or turn upside-down a few times.
Wait a few seconds and you’ll see the reagent change colour. Then compare the colour in the vial with the colour chart on the plastic tester to determine the active chlorine level. After that, wait a couple minutes and compare again to determine the chlorine residual level.
You’ll then do another test if the chlorine residual is below 3.0. Fill the large tube on the right to the top solid line with pool water (again from a depth of 18 inches). Add one drop of solution, a chlorine neutralizer, and mix it by gently swirling. Then add five drops of the phenol red indicator, and again mix by gently swirling. As with testing the active chlorine, you’ll compare the colour with the pH colour standards on the plastic tester.
Between 1 part per million and 3 parts per million is the ideal amount of chlorine. If the reading is not at this level, you’ll need to adjust the chlorine amount you regularly add.
Testing pH
The water test kit will come with a chart that will tell you how much dry acid or muriatic acid to use to achieve the correct pH (positive hydrogen) levels in your pool. Understand that if the water is too acidic it will be corrosive, which could damage the pool’s plaster finish and vinyl liner as well as have a highly negative effect on anything that is made of copper, such as the pool heater. Acidic water will also cause erosion of your heat exchanger long before its time.
The right pH for a swimming pool is 7.4 and 7.6 parts per million – this is ideal for the comfort of your skin and eyes plus the pool finish and equipment.
To test the pH, drop the water tester straight down rather than at an angle. It’s important to use the cap and not the palm of your hand to mix the chemical as your skin pH could affect the reading.
You’ll also want your test to give you what is called an acid demand reading – this will tell you, by drops, how much acid to put in the swimming pool. In other words, the tester colour will change colour as you add the acid to indicate when you’ve reached the ideal balance. As an example, two drops will change the pH from 7.8 to the correct level of 7.6.
Testing Water Alkalinity
The pool water alkalinity level is also crucial since if it’s at the correct balance, it will keep the pH from jumping too high or too low.
To measure this, a titration test is optimal – you’ll add the drops one at a time until the water turns clear. Alkaline testing is different from testing pH levels in that you don’t cap the chemicals to mix them for a result. Bear in mind however that pool test kits vary in the colours they compare – for example, mine changes the colour from blue to clear. The correct levels would be 120 parts per million.
Ideally you should firstly add a chlorine neutraliser when doing this test because your pool’s chlorine levels will affect the alkalinity reading.
Conclusion
Swimming pool chemicals need to be monitored carefully to ensure your pool water is as it should be. Once you’ve performed your tests, make sure to rinse your plastic tester (anywhere but the pool!) to get rid of any residue that would affect future results and then store it far from reach of children or pets.
It’s a good idea to do a pool water test weekly during the swimming season, following the above tips and the products quantities listed in your instructions. If you find balancing your pool to be tricky or too time consuming, you could always enlist the help of a pool professional once a month. After watching them a few times, you’ll soon get the hang of it.
About the Author: Andrew Astonville is an independent advisor on swimming pool chemicals.
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