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A Guide to Proper Pool Water Chemistry

Categories: How To Guides, Chemicals, Maintenance & Upkeep
Summertime is the ultimate opportunity for pool owners to show off their backyard wonderland, complete with abundant sunshine, barbecue aromas wafting through the warm air and - of course - picture perfect pool water tempting one and all to a refreshing swim.

Yet those same owners often are intimidated by the prospect of maintaining their water themselves, given all the potential problems involving chemistry and equipment, the wealth of products designed to handle those problems, and newer trends in the pool industry (saltwater pools, UV sanitation, etc.). Often they take the approach that the proverbial “pool guy” is the best bet for keeping their pool presentable over time. But this is a common (and often expensive) misconception that can be overcome with some initiative and a regular plan of maintenance.

What to monitor

Water chemistry is actually fairly simple to maintain under normal use and manageable weather conditions. Experts advise there are just a handful of basic factors necessary to keep under control:

  • pH level
  • total alkalinity
  • calcium hardness
  • "free" chlorine (chlorine that hasn’t yet begun to dissolve)
  • chlorine stabilizer

Water’s pH level refers to its level of acidity, commonly measured on a scale of 0 to 14. A pH level below 7 means water is overly acidic, whereas a level approaching 8.0 renders water “basic”, or alkaline. This works hand in hand with total alkalinity, which measures (in parts per million) alkali metals like sodium and potassium that occur naturally in pool water.

  In short, a stable level of total alkalinity helps keep the water’s pH level under control because the manageable presence of these metals (ideally 80-120 ppm) moderates acidity.

Finally, there a couple of measurements directly related to the level of chlorine in the pool. “Free” chlorine is sanitizer that has yet to begin the dissolving process, and chlorine stabilizer (cyanauric acid) is used by some pool owners to prolong the usefulness of chlorine by protecting it from direct sunlight. Both of these have obvious benefits for keeping the pool clean, but like anything else need to be kept under control. Free chlorine, like pH level, is measured on its own scale and its optimal range is 1.0-2.0. Chlorine stabilizer is generally meant to stay within a range of 40-60 ppm.

Calcium hardness, similarly, measures the effect of minerals – as opposed to metals - on pool water, usually those present in the local water supply (pool professionals recommend a range of 200-300 ppm here).
Why levels are important 

Anyone who’s had trouble keeping their eyes open while swimming underwater has experienced firsthand the perils of poor water chemistry. But chemical levels out of the various desired ranges can also produce plenty of other problems, like staining of liners and tiles, potentially costly corrosion and swift degradation of metal equipment like heaters, lights and filters, to say nothing of the general unsightliness of cloudy or murky pool water.

Just as important is the hindrance of proper sanitizing of the water. A lax attitude toward water maintenance could result in a health hazard in your own backyard!

How to test water and understand results

Fortunately, testing pool water can be done by anyone with a decent amount of patience and the proper tools. Test strips and kits, which check the aforementioned levels, are the most prominent methods for evaluating a water sample, and they make it easy to pick out anything amiss.

Pool professionals suggest testing water a couple of times per week in the heart of swim season, when the harshness of sunlight and body oils and fluids can combine to create problems. It’s easy to forget to be so vigilant, but water problems that are diagnosed early generally require much less corrective action.

And it’s important to remember that deviations from acceptable ranges for chemicals (especially when first beginning the process of “opening” the pool after winter or a period of storms) are common and usually simple to correct. And everyone knows what pool water should look and feel like. Chemistry problems typically reveal themselves by being far apart from these expectations.

The various chemicals available and how to administer them

If you find that you have an imbalance in the pool water that you test (pH level too high, calcium hardness too low, etc.), there are a host of products available to get things back under control. The pool typically needs to be off limits for a couple of days while these chemicals are administered and the adjustments take effect, but that’s a trivial price to pay for perfect water the rest of the swim season.

For instance, a common problem in pools is "soft water," a condition often caused by a lack of minerals in the water source or by steady rainfall. Soft water, over time, can corrode equipment irreparably. But a simple solution is the use of calcium supplements such as this one from Pool Pals. The powder is poured next to the pool's intake and improvement is almost immediate. Better yet, your testing tools let you know exactly what difference you're making and what, if any, required action remains.
  Another problem pool owners sometimes experience, particularly in the hottest days of summer, is chlorine deprivation from direct sunlight. A common reaction from newer owners is to increase their application of chlorine to the water - but a cheaper, far more efficient strategy is to use a product like Pool Pals' Water Conditioner, which gives your existing chlorine much more staying power. And, of course, an adequate test system will give you an idea if you're using the right proportions here as well.

Other tools, such as algaecide and shock treatment (a heavy dose of chlorination), can also help the process of achieving optimal water chemistry and have their own benefits when used periodically even if your other levels are fine. 
Getting into the habit of checking chemistry long-term

The takeaway from this (hopefully) should be that maintaining refreshing, stable pool water can be achieved with a regimen of routine maintenance and an understanding of its optimal makeup.

The pool guy can still be called in occasionally to make sure everything is in order, but the eye test – and regular use of common tools – are usually enough to make your water ideal throughout the season. This becomes second nature over time, and also helps you save money and get much more enjoyment out of your backyard investment.

Still have questions about water chemistry or what chemicals you might need? We're here to help! Feel free to comment below or give us a call and we'll do everything we can to get you the info you need!
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Pool Supply Unlimited is an e-commerce company that loves water. We love to pump it, filter it, heat it, chlorinate it, light it up and stare at it while we're barbequing a fat, juicy steak. There are real pool professionals working here. Our guys have seen thousands of pools in their careers, no exaggeration. We are based in Southern California and can land most products to your door (within the 48 contiguous states) in less than a week.
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