You could have inadequate filtration for your pool's size or low or inconsistent chlorine levels. Bad water circulation with dead spots or pool imbalance in your pool chemicals are also two big culprits. One or any of these factors can kick off a pool algae bloom that spreads across your pool.
Bleach is great for killing algae (and other organisms that may lurk in your tanks) and for keeping it from coming back.
A word on Filtration. If your filter is not running long enough per day, or is undersized, old or ineffective, this will exacerbate an algae problem. Effective filtration is operating the pump long enough so that all of the water in the pool is filtered at least once per day.
Barley straw is a natural way to fight algae. On contact with water, the straw starts to break down, and as it does so it releases peroxides into the water which combat algae. Available in mini bales, or as a concentrated extract of barley straw liquid, it's a natural way of chemically fighting algae.
Black algae is a stubborn organism. Its protective outer layer sets roots into the surfaces it clings to. This makes it one of the toughest algae strains to get rid of.
Shock Your Pool
Shocking is the process of adding chemicals to your pool to raise chlorine levels and kill bacteria and algae. We recommend using a calcium hypochlorite shock to treat your algae problems.
If the pH becomes too high (over 7.8), it prevents the chlorine from doing its job. If you're not checking the pH and it has risen too much, you could be adding the right amount of chlorine, but it can't work correctly, and algae will begin to grow.
So, this one is kind of obvious, but chlorinated water does not grow algae. If you always keep your chlorine levels consistently between 3-5 ppm your water will stay blue.
Whether mild or severe, it isn't recommended. Significant amounts of swimming pool algae welcome a breeding ground of harmful bacteria that feed on algae. These bacteria pose health risks to swimmers, most commonly resulting in a skin rash. It can also cause various bacterial infections of the ears or eyes.
If you have an algae problem, your best friend is white vinegar. White vinegar can quickly kill algae but is not harmful to birds, insects and the majority of plants. Use a mixture of one part water to one part white vinegar to spray down the area and kill the algae.
Thick layers of algae, called algal blooms, may form when nutrients (mainly phosphorus and nitrogen) build up in the water in amounts in excess of naturally-occurring nutrients. Fertilizers, pet waste, improperly functioning septic tanks, grass clippings, leaves, and other yard wastes are all sources of nutrients.
Algae blooms can occur when a combination of suitable environmental conditions exist for abundant algal growth (e.g., increased nutrients, warmer temperature, abundant light, and stable wind conditions).
Since Algae is like most plants that thrive off sunshine, depriving them of light will prevent and/or eliminate its growth. The key is to completely shade the tank or aquarium from light for several days (A minimum of 4 day and a maximum of 7 days).
But as it turns out, copper pennies do a pretty good job of keeping algae away for a few days! Pennies made before 1982 contain copper and according to Google, “copper kills algae by binding to it, which damages the algae cells, causing them to leak and die.” I tossed in 10 pennies and waited for the results.
Pools can immediately turn green after shocking when they have metals like copper in the water. These metals oxidise when exposed to high levels of chlorine which makes the pool water turn green. Adding a metal control product such as Zodiac Metal Remover will help to restore the pool water.
If the water is too warm it invites bacteria and algae to grow and bloom. Water temperatures in the 85 degree range is an invitation for bacteria to curl up in a corner of the pool and begin growing.
Depending on the severity of your algae growth, you'll need to add 2-4 doses of shock. And it's normal to see cloudy water after killing algae with shock. The water should clear up after you run your filter. Just be sure to vacuum and brush your pool before using shock.
It's often recommended to shock your pool once a week. If you don't do it every week, you should at least do it every other week. This is necessary to maintain your pool's water chemistry. If you have a lot of people over in your pool or have a party, you may want to shock your pool more frequently.
Using baking soda in your pool is one of the easiest but most efficient ways to get your backyard ready for summer. This pool idea is loved by experts who recommend using this homemade remedy to increase the alkalinity and pH level of your pool – and treat black algal growth on your swimming pool wall.
Scrub the black algae away with a good, stiff pool brush. This will help break down the protective layer and make it easier to treat. Break a chlorine tablet in half and rub it directly onto the affected areas. The chlorine treatment will kill the algae's roots and prevent it from coming back.
How long will it take to clear the pool? A fiberglass pool in its worst condition can be algae-free in 24 hours. For a vinyl liner pool, the process can take 3-4 days. For a concrete pool, this can take a week or more.