How to Reduce Chemical Use in Your Pool and Spa

Chemicals such as chlorine make swimming pools possible. Without them, you wouldn’t have the assurance that you won’t get sick or have to swim through algae, oils and other unpleasant organics and contaminants.

While chemicals are necessary, we’d all like to reduce our exposure to them, so here are some ways to get as close to pure water as possible while keeping it safe.

Increase pump run time

The best way to reduce chemical use is to improve filtration and keep the water moving. We don’t want to run the pump more than necessary, but trying to reduce run time too much doesn’t save money. What you save in electricity may be offset by increased labor and chemical use. Use these guidelines as a starting point and adjust as necessary:  8-12 hours per day for an infrequently used pool, 14-20 hours per day for a moderately used pool, and 18-24 hours per day for a heavily used pool.

Keep Stabilizer and TDS at correct, low levels

Outdoor pools need stabilizer (cyanuric acid) in the water to keep the chlorine from leaving too quickly. A good level is 30-50 ppm. Anything above that and free chlorine will not do its job efficiently since it is too tightly bound to the stabilizer. High stabilizer levels require much higher amounts of chlorine in order for it to be effective. Texas law allows stabilizer levels as high as 100 ppm, but recent research shows that this is way too high. If your stabilizer is too high, it’s time to drain some water and refill. What causes high stabilizer levels? The use of trichlor tablets adds stabilizer continuously which eventually results in too high a level. What to do? See the Pulsar® section below.

Total Dissolved Solids (TDS) should be kept below 2000 ppm. A target of 1500 ppm is even better. If TDS is too high, all chemical reactions slow down including sanitation and oxidation. As TDS climbs, you’ll need more chlorine to keep the water safe. TDS is lowered by draining a portion of the water and refilling.

Keep pH at 7.2-7.6

If your pH is too low, swimmers will be uncomfortable and your equipment and pool surface will be harmed over time. A high pH causes scale and keeps your chlorine from being effective. Your test kit may show that you have a good free chlorine level (2-3 ppm), but it won’t be in the form that effectively kills germs and algae. Don’t allow pH to stay above 7.8 since chlorine doesn’t kill pathogens quickly enough at high pH. If your pH runs in the higher part of the recommended range, keep the free chlorine level at 4-5 ppm.

Watch Combined Chlorine Levels

When you test for chlorine, make sure to use a DPD kit that allows you to test for free and combined chlorine, also known as chloramines. Combined chlorine is used-up chlorine that is ineffective as a sanitizer. When you have more than 0.2 ppm combined chlorine you must shock to remove it. It may seem counterintuitive to add more chlorine in order to reduce your chemical use, but the extra chlorine will dissipate after removing the chloramines, leaving less chemicals in the water.

Don’t Use the Pool as a Bathtub (or a bathroom)

It’s tempting to jump in the pool after a run or a sweaty session of yard work, but be aware that this uses a lot of chlorine. Rinse off first and keep that extra organic material out of the water including not only sweat but excess suntan lotion, oils, and sunblock.

Don’t be tempted to pee in the water. Urine contains nitrogen products that form a lot of chloramines in pool water, using up free chlorine and giving you a bad chlorine smell.

Speaking of Sunblock…

Sunblock works best when it soaks in for 15-30 minutes before you go in the water. This is even true of “water proof” sunblock. Don’t slather on the sunblock and jump in the water. Much of it will wash off in the water, requiring more chlorine and enzymes to get rid of it.

Cool the Water

Algae and pathogens love warm water. This means as the water heats up, you will have to use more chlorine and algaecides to keep them under control. In Austin, our water can reach the 90’s by the end of August. And, of course, people swim more the hotter it gets, requiring even more chlorine to oxidize organic matter.

Install a fountain that you can run at night to cool the water. The Polaris Waterstars® fountain works well for this.

UV System

A great way to reduce chemical use is to install a UV system. UV systems kill pathogens, and algae. They also get rid of chloramines. You must still have some free chlorine, at least 1.0 ppm, but you will use a lot less chlorine product to maintain this level. You will seldom, if ever, have to shock the pool or use algaecides.


Most pools use trichlor tablets for chlorination. Trichlor tablets are formed with stabilizer (cyanuric acid). Their use often results in high stabilizer levels. This isn’t always a problem in gently used backyard pools since backwashing filters removes water that is then made up with fresh. If your pool gets a lot of use that requires a lot of chlorine, consider switching to a calcium hypochlorite system such as Pulsar®. This system is an automated solution that uses calcium hypochlorite tablets that do not contain cyanuric acid. Pool owners that use the Pulsar® system are very happy with the water quality and lower chemical use. Call us today for a free estimate.

Salt Water Pools

You may have heard that salt water pools use less chlorine. This isn’t true. Salt water generators use electrolysis to produce chlorine from salt. They do have the advantage of not adding extra stabilizer, but otherwise, there is no difference in the amount of chemicals you’ll typically use.


Ionizers produce copper and silver ions which are effective algaecides and sanitizers when used correctly in specific situations - especially as a backup to other sanitation methods. These ions are not fast acting and don’t oxidize organic matter, so chlorine is still required. Correct pH levels are critical as staining can occur when pH is a little too low. We find these systems don’t work as well as we’d like them to in pools in our hot weather, and we don’t recommend them.

Solve Problems with Best Maintenance Practices

Follow the best practices above to reduce chemical use. Avoid trying to “solve” problems by simply adding more chemicals until you have made sure that you’ve first looked at circulation, water balance, sanitation, and hygiene. If you need help, call us! 512-873-8565.

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