Backyard swimming pools are designed to more-or-less take care of themselves, but they are far from maintenance-free. Keeping the water sanitary and safe takes a regular regimen of testing and adding chemicals, as needed, to maintain critical levels of sanitizers, acidity and water hardness, among others. It's important to become familiar with the components of the circulation system and how to adjust each one, because you may have to do that from time to time. You should also be prepared for unusual situations, such as pool parties or heavy rainstorms. You might have to shock the water or change the pool level after such an event.

Screening debris from the surface of a pool.
credit: Photo by aftab chandsha on Unsplash
If you're new to pool maintenance, spend some time becoming familiar with the pool equipment.

Know Your Pool Controls

Every pool has a circulation pump and a filtration system, the components of which are usually near the pool -- sometimes in a shed. The system includes a pressure gauge, which provides important information about the conditions of the pump and the filter. Some pool systems include a third component -- a chlorinator -- which converts salt in the water into free chlorine. If your pool has a chlorinator, you may have to adjust it from time to time to raise or lower the concentration of free chlorine in the pool.

Types of pool filters: Pool filters come in three types -- sand, diatomaceous earth (DE) and canister. If you have a sand or DE filter, your system should have a multiport valve, which allows you to backwash the filter when the pump pressure rises more than 8 to 10 psi from normal. You don't have to backwash a canister filter; you simply remove it and hose it off. A canister system doesn't need a multiport valve, although there may be one for directing water to waste when you use the pool vacuum.

Hooking up a pool vacuum: If your system includes a built-in vacuum, you usually connect the hose to the vacuum inlet in the skimmer. The connection is usually designed to lock together with a quarter-turn of the vacuum connector. When you use the vacuum, be sure to choose a multiport setting that bypasses the filter. The "waste" setting is usually the best one.

Keep the manuals handy: A time is bound to arrive when you need to know more about how your system works so you can troubleshoot a problem. If you have paper copies of the manuals, you'll have that information at your fingertips. If you lost them, you can usually find online copies by searching the make and model of the component for which you need information, followed by the term "manual."

Testing and Balancing Chemicals

While you can always take a sample of the pool water to a pool dealer for testing, most people would rather do their testing themselves. You have a choice between test strips and liquid tests kits, although test strips are probably more accurate. The higher quality the test kit, the more accurate the results. Just dip a test strip into the pool water, and the color of the strip will tell you the free chlorine concentration, pH and total alkalinity, among other things.

Balancing Chemicals

The importance of maintaining pH: The pH of the pool water, which is a measure of its acidity/alkalinity, should always be in a range from 7.2 to 7.6, which is slightly alkaline. When it's outside of this range, you'll have trouble maintaining sufficient chlorine levels, because acidic and alkaline water quickly degrade hypochlorous acid, the sanitizing agent in a chlorine pool. Balancing the pH is a precursor to most chemical adjustments and to shocking the pool. When you need to lower pH, use muriatic acid or dry acid, and when you need to raise it, use baking soda or soda ash. All these chemicals are available at any pool store.

The free chlorine concentration in a typical backyard pool should be between 1 and 3 parts per million. "Free chlorine" isn't the same as total chlorine, because the sanitizing action of chlorine involves forming compounds with contaminants, and once these compounds have been formed, the chlorine is no longer available. Sometimes you have to shock the water to break up these compounds.

Total alkalinity is related to pH, but it's a separate measurement. If the TA is too low, the water becomes corrosive, whereas if it's too high, the pH becomes difficult to maintain, and the water can become cloudy. Total alkalinity should be in a range between 80 and 120 ppm. Lower TA with muriatic acid or dry acid, and raise it with baking soda.

Calcium hardness is another important parameter, and while your don't have to test it as often as other chemicals, you should test it at least once or twice a season. The ideal level is between 200 and 400 ppm. Less than that, and the water could become corrosive; more than that, and the water will probably turn cloudy.

Shocking the Water

The term "shock" means to quickly raise the free chlorine level to 10 ppm or more. This treatment kills pathogens and restores chlorine locked up in compounds called chloramines. When your pool smells of chlorine, it doesn't mean the chlorine level is too high. It means the chloramine level is too high, and the remedy is to shock the water.

You can buy pool shocks, which are powders that you add to the water, or you can shock by simply adding lots of chlorine. Even chlorine bleach works as a pool shock. To ensure you add the right amount, you'll have to calculate the volume of water in your pool. The more water in the pool, the more shock you need to add.