So, you’ve been away for a while and come back to find a nasty green slime has invaded your swimming pool. Or maybe a pool party has left your pool looking less than pristine. Don’t worry, you’re not alone. Swimming pool algae-organisms that leave a green film of the sides of the pool and tinge the water greenish, too-are one of the most common problems pool owners face. Fortunately, the best way to get rid of swimming pool algae is straightforward, if a bit of a hassle.
Pool Algae Basics
First of all, it’s important to understand how the swimming pool algae got started. There’s really only one reason: the chlorine level in the pool dropped below 1 ppm. To keep algae at bay, the free chlorine level in the swimming pool needs to be between 1.0 and 3.0 ppm. Some specialists recommend a minimum level of 1.5 ppm. You can find out the chlorine level in your pool by using a special test kit available from pool supply stores.
Of course, once the problem is there, you need to know how to get rid of swimming pool algae. To get rid of this ugly green stuff, the most efficient method is to use an algaecide followed by a chlorine shock treatment. Algaecides are specifically designed to kill algae, whereas chlorine is meant to sanitize the pool water and prevent algae and bacteria from ever getting started.
Brush the pool
Before you start with any chemical treatments, though, use a pool brush to clean the algae off the sides and floor of the pool. Breaking up the algae like this helps the chemicals do their job faster.
Use an Algaecide
After brushing down the pool, run an algaecide treatment. Always use this treatment before using chlorine. If you add the chlorine too soon after adding the algaecide, the chemical reaction can stop the algaecide from working. There are two main types of algaecide: metallic (copper and silver) and quaternary ammonia. Both types are effective, but ammonia tends to be used more often because it’s both less expensive than metallic algaecide and not as likely to stain the pool. The only problem with it is that it tends to suds up, which some people find annoying. Also, if you have black algae, rather than the usual green, look for an algaecide specially formulated to kill this tougher species of algae. Whichever you choose, the algaecide should contain at least 30% active ingredient (metal or ammonia). Less than that and the treatment isn’t likely to be effective. After you add the algaecide, give it at least a day to work before do anything else with the pool.
Run a Chlorine Shock Treatment
To really get rid of swimming pool algae, the next step is a chlorine shock treatment. A shock treatment raises the pool’s chlorine level to 5 ppm, a level that will kill off any algae or bacteria that may be lurking in the water. To run this treatment, you’ll need the granular form of concentrated chlorine known simply as “chlorine shock.” The anti-algae treatment is similar to the weekly maintain shock treatment, but you’ll need a larger amount of chlorine. Check your pool manufacture’s instructions for the exact ratio of chlorine to water. Remember that chlorine shock must be dissolved in a bucket of water before you add it to your swimming pool. Always add chemicals to water; never add water to chemicals.
Keep your pool’s filter system running when you add the chlorine shock. As you’re running the shock treatment, keep an eye on the filter system. You’ll most likely need to clean dead algae out of the filters to prevent pressure from building up. You can easily tell when the algae are dead because they’ll lose their color and settle on the floor of the pool or remain suspended in the water. There should be no green left in the pool. In some advanced case of algae bloom, one shock treatment may not be enough to get rid of all the algae. If you don’t see the algae die within 24 hours, run a second shock treatment.
Vacuum the Pool
Once the algae are dead, vacuum them up out of the swimming pool. Also, remember to clean out the filters again so no algae are left in the pool to give a foothold to another algae bloom. Finally, check the chemical levels in the pool and make sure they’re correct for your pool.
Algae are a common nuisance for many swimming pool owners. With proper maintenance, though, it’s not too hard to keep algae away. The best prevention method is to keep your pool clean by making sure the free chlorine level is high enough and follow the pool manufacture’s guidelines for upkeep. Keep your pool in good shape and you’ll be able to avoid the hassle of using algaecides or, worse, having to drain the whole pool just to get rid of swimming pool algae.