It may surprise you suddenly: one day you walk outside and your pool has turned green. How did this happen? There are several causes of a green pool, but luckily there are many ways to fix it.
How did my pool turn green?
In warm summer months especially, algae can begin to takeover your pool. This is caused by imbalances in chlorine and sanitation. If your chlorine levels dip too low, algae can grow rapidly. Maintaining proper sanitation levels in your pool is key to preventing green water. A licensed pool builder can also help keep your pool sanitized.
Even if you test your sanitation levels regularly, many external forces can affect your pool. Extreme heat or weather changes (such as the ones we have in Houston) are a prime suspect. A dirty pool with lots of debris can fuel algae. Even your pool filter being clogged can cause algae overgrowth.
You should also keep in mind that a green pool may not be safe to swim in. You run the risk of getting sick due to algae or bacteria in the water.
There may be many causes of a green swimming pool, but luckily there are many ways to tackle the issue.
What can I do?
Test the pH levels
Although surely your pool is imbalanced, it’s important to test the pH levels prior to treating. If you don’t balance the pH levels during treatment, your pool could become cloudy. As a rule of thumb, pH levels for balancing should be between 7.2 and 7.8, which is slightly high but will allow the shock treatment to be effective.
Clean out debris
If your pool has become dirty or has lots of debris in it, you’ll want to clean this out prior to treatment. Leaving debris in the pool can alter the chemicals. It can also disturb the shock treatment. Also be sure to brush the pool walls as well as you can.
Shock treatment
The most vital step to removing algae from your pool is to use shock treatment. This basically means you will over-chlorinate your pool to kill the algae and bacteria that have developed. Be sure to do the proper calculations to determine how much shock your pool needs.
Pour it in slowly around the perimeter of your pool. You will need to test your chlorine levels regularly to make sure it stays at the correct shock amount. The pool should go from green, to cloudy, to clear again.
Run your filter
As the shock treatment kills the algae, you will need to run your filter in order to remove it. This may require regular maintenance over a few days, depending on how dirty your pool was to begin with. Run the filter for at least 24 hours. After each session, be sure to clean it out so you don’t experience algae buildup. After cleaning the filter, continue to scrub your pool clean.
Extra steps
For extra precaution, you can also add an algaecide to your pool. This is a product that aids in killing algae. You can also add a flocculant, a product that clumps the algae together for easier filtering.
Continue testing
Consider an overnight chlorine lost test (OCLT) to determine if there are any remaining algae in the water. Consistently testing your chlorine levels will ensure that your pool does not turn green again. You also want to test the levels to be sure they’re back to normal before allowing anyone to swim in the pool.
Still having trouble?
There could be multiple reasons why your pool persists being green. It’s possible that if you rush the shock treatment or don’t properly run the filter, it will not resolve the problem. Also, you cannot use an algaecide by itself to clear a pool. It is more of a preventative measure. It’s also important that you start out with step #1: testing the pool’s levels. If the pH is too high, the chlorine can be ineffective.
If you need help clearing your green swimming pool, contact 3D Pools and Landscape. We are licensed pool builders in Houston and Katy with over 20 years of experience.
