The other methods listed below are faster, but may not fix underlying sanitation concerns. They are also more expensive and can have unwanted side effects.
Make sure the brush is compatible with your pool. Steel brushes work well on concrete, while nylon brushes are preferable for vinyl pools. [1] X Research source
Wear gloves, eye protection, and clothing that covers your skin. After use, wash hands and inspect clothes for chemicals. Avoid inhaling the chemicals. Use caution when handling in windy weather. Always add chemicals to water, never water to chemicals. Do not place wet scoops back in container. Store chemicals in sealed, fireproof containers, away from children, on separate shelves on the same level (not one above the other). Many pool chemicals explode when they touch another pool chemical.
Test kits that use tablets or droppers are much more accurate than paper test strips. [4] X Research source If pH levels are back to normal but total alkalinity is above 120 ppm, check the pH reducer label for instructions to bring total alkalinity down between 80 and 120 ppm.
Avoid calcium hypochlorite if you have hard water. All hypochlorite products are flammable and explosive. Lithium is relatively safer, but much more expensive. Avoid granular or tablet chlorine products (such as dichlor or trichlor), which contain stabilizers that should not be added to the pool in large quantities.
Warning — liquid chlorine will explode and produce corrosive gas if it touches chlorine tablets or granules. Never pour the liquid chlorine into your pool skimmer or anything that contains these products. Because UV rays in sunlight break down chlorine, shocking is most effective when added in the evening and left overnight.
If your chlorine levels are higher (2–5 ppm) but the algae is still there, keep maintaining these levels as usual for the next couple days. If chlorine levels have risen but are still below 2ppm, shock a second time the next evening. If there was no significant change in your chlorine levels, your pool likely has too much cyanuric acid (more than 50 ppm). This comes from using granulated or tablet chlorine, and can “lock” your chlorine into unusable forms. The only way to fight this is to shock repeatedly (sometimes many times), or to partially drain your pool. Large amounts of leaf litter or other objects in the pool can also eat up your chlorine. If the pool has been unused a long time, this could take a full week and several shock treatments.
A well maintained pool has roughly the following values: Free Chlorine: 2-4 ppm, pH: 7. 2 – 7. 6, Alkalinity: 80 – 120 ppm and Calcium Hardness: 200 – 400 ppm. [7] X Research source Slight differences in standards are common, so a small deviation should not be an issue.
If you’re having trouble getting all the algae, add coagulant or flocculant so it clumps together. These are available at pool stores, but may not be worth the purchase for a home pool.
Some algaecide products are not powerful enough to treat an existing bloom, especially if you have black algae as well. Ask a pool store employee for help, or find a product with 30%+ active ingredients. Quaternary ammonia algaecides (“poly quats”) are cheap, but cause your water to foam. Many people find this annoying. Copper-based algaecides are more effective, but expensive. They usually stain your pool walls as well. After adding the algaecide, wait at least 24 hours before adding other chemicals.
Daily testing is ideal, especially in the week or two following an algal bloom. Always test at least twice a week during the swimming season.
Make sure to follow instructions for regular prevention, not for existing algae blooms. Too much algaecide may stain your pool or cause foaming.
Pool professionals disagree over acceptable phosphate levels. 300 ppm is probably low enough unless you have recurring algae problems. [12] X Research source
