Pool Chemistry – A Pool Owner’s Basic Need-To-Know Guide

Monitoring and understanding the chemistry of your swimming pool can be tricky when first starting out. Don’t let it overwhelm you. With the basic knowledge in this guide and a little bit of effort, you’ll know everything a mindful pool owner should know, and more.

 

Testing Your Pool Water.

 

Many pool owners don’t put much thought into how and when they test their pool water. Just dip the strip in the water and compare it to the chart, right? Well, maybe, but there’s more to it than that. There are appropriate times to conduct the test and certain places in the pool it should be done.

 

The best time of day for testing pool water is at dusk, at least four hours after the last swimmer has left the pool and at least 8 hours after a rain or wind storm. Weekends are often the most convenient days for swimming pool owners, but you must be mindful of the heightened presence of contaminating content on those days: neighbors mow the lawn, fertilize their yard, sod gardens, et cetera, all of which can contribute to false readings. Note that shocking your pool should definitely be done at dusk, as it will give the treatment time to take effect before the sun comes out (otherwise, the sun can burn off much of what you added before it reaches breakpoint oxidation).

 

The best place in your swimming pool to test the water is an area that is representative of the whole body of water. So, the water coming back into the pool from the filter isn’t your best bet. The ideal place is midway between the shallow and deep ends away from any return lines and skimmers. In that area, dip your testing strip or water collection container down to elbow depth, and if you are using a pool water testing strip, leave it submerged for 30 seconds. From there, follow the directions for your testing product. This seems obvious, but manufacturers’ instructions may vary, so be mindful of any variations. If you are using a test tube or other water vessel, ensure it is clean prior to sample collection to avoid any cross contamination

 

If you bring your water to a retail store or service center for analysis, handle the collected sample with care. As a small sample of water it will be affected by the environment much more quickly than your pool. If, for example, the container is left in the back of a heated car for 5 hours prior to testing, your reading may not reflect the reality of your swimming pool’s water. The test, at that point, should be considered unreliable.

 

Chlorine.

 

Maintaining a proper level of chlorine in your swimming pool is critical to the health of your pool water. Although filters remove suspended particles and regular cleaning is a must, you must still confront the development of bacteria and algae. In order to do so effectively, you should maintain a residual chlorine level of 1.0 - 3.0 ppm (parts per million). Do note, however, that maintaining the proper level will depend on the amount of traffic your pool experiences. If swimming pool traffic is heavy in your backyard, shock your pool once a week with a 3 to 5 times higher than normal dose of chlorine. Of course, don’t enter the pool until the chlorine level returns to normal.

 

You should also be mindful of how much direct sun exposure your pool is getting because the sun’s UV rays break down chlorine. Cyanuric Acid, typically packaged as a "Conditioner" or "Stabilizer", is a chemical that protects chlorine from being destroyed by the sun, so adding it into your swimming pool at the beginning of the swim season will help maximize your chlorine’s effectiveness throughout the entire swim season.

 

pH Level.

 

Your swimming pool’s pH level is extremely important and should be tested once per week. pH level, roughly speaking, is the measure of how acidic your pool water is: the ideal pH for pool water is around 7.5, but a range between 7.0-7.6 is considered acceptable. A pool in that range is considered "balanced." Below that, your pool will be too acidic, causing discomfort to swimmers and potentially corroding or otherwise damaging your pool and pool equipment. Above that, your pool will be too alkaline, causing murky or cloudy pool water and increased calcification. Either extreme dramatically reduces the effectiveness of the pool’s chlorine, so it’s very important to pay attention to these levels by employing frequent testing.

 

Making Chemical Adjustments.

 

So you got a reading that is either abnormally high or abnormally low, what should you do? Nothing, yet. Check it again after waiting 24 hours, and if it is not back to normal by then, you should begin making adjustments. Remember, adjustments should be small to begin with. After making the relevant changes, test the swimming pool again six hours later. Repeat this process as necessary

 

While adding multiple pool chemicals is sometimes necessary, you should never put all your chemicals in at the same time. Wait between 4 and 6 hours between treatments. If you mix different chemicals into the pool at the same time you run the risk of anything from decreasing their effectiveness to causing an explosion.