Why is my pool green?

This is the most common problem with pools this time of year. New customers will call and say the pool was fine all winter with no issues, and almost overnight the pool has turned an impenetrable pea soup color. What has usually happened is that the pool has actually had problems through the winter, either with filtration or chemical balance, and it’s only as the temperature warms up or a storm dumps a lot of organic matter in, that the pool suddenly spirals out of control.

The first step to getting your pool under control is to get chemicals balanced again. The primary cause of green pools is running out of Free Chlorine. Figuring out why the pool has no Chlorine is beyond the scope of this article, but you need some sort of agent to kill the algae spores. If you don’t kill the algae, it will just keep reproducing and you’ll never get ahead. I do not recommend using an algaecide early on in the recovery process. Try Chlorine first because it’s cheap and efficient. Only move onto algaecides if you are having a chronic condition that Chlorine is not resolving.

Also check you pH and Alkalinity balance. Chlorine effectiveness is dependent on pH. If your pH is high you will need a lot more Chlorine to have the same effect.

The second major component is filtration. As we talked about before, different filter types are more effective with clearing green pools. Make sure that your filter is clean and working properly. A DE filter with broken grids will be of little use in a green pool. It’s a good time to schedule a DE Filter Service or Cartridge clean if it’s been awhile (more than 6 months).

Get everything in good working order, and the chemicals balanced, and you should start to see an improvement fairly quickly. You can run the filter for longer as well, even 24 hours a day if you like, until it clears. If you don’t see any difference within a few days, you should call in the pool experts to take a second look.

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One Response to Why is my pool green?

  1. admin says:

    As a followup, a customer called today and seeking help with clearing his green pool. He’s not a current customer and has been trying to clear the pool himself. The filter will only run about an hour before it needs to be backwashed because the water is so thick with algae. He’s already dropped 17# of shock and it’s still unable to get a Chlorine residual. It’s not unusual to expect to go through as much as 50# of chlorine before you kill everything in the water and can start really trying to get rid of the now dead stuff floating around.
    He basically has two options to choose from. He can continue to chemically treat the water on a daily or more basis until he can maintain chemical balance, and then call us to floc the pool and drain the nasty stuff to waste, or he can bite the bullet and have us come drain and clean the pool. Draining and cleaning the pool with a powerwasher is going to be more expensive obviously, but he can be swimming this weekend and not have to deal with trying to clean the pool in addition to his regular full time job.
    As always, if you have any questions, or you need any of our services, like drain and cleans, or vacuum to waste with a flocculant like “Down and Out”, give us a call at 214-989-3888.