Yes, in many cases, you can fix a green pool without draining it. If algae is causing the problem and your pool equipment is working properly, you can often get the water clear again with the right treatment and filtration. You just need to figure out why the water turned green in the first place before deciding what to do next.
In this post, we’ll cover when green pool water can be treated without draining, how to clear it, and when replacing some or all of the water may actually be necessary.
Green pool water can usually be treated without draining when algae is causing the problem. Algae often develops when chlorine levels drop, circulation is poor, or the water chemistry gets out of balance.
In that case, the goal is to correct the water chemistry, kill the algae, and remove it through brushing and filtration.
Ready to get that water from green to clear? Here are the basics of fixing a green pool without draining it.
The first thing you should do is figure out the water chemistry situation. So, before you add anything to the pool, test the chlorine, pH, alkalinity, and stabilizer levels. That gives you a clear picture of what is actually off rather than guessing.
As a general starting point, aim for:
Your chlorine target will depend on the stabilizer level and the severity of the algae problem, so this is one area where the test results really matter.
If any of those numbers are way off, correct them first. Once the water is in a better range, the chlorine can do its job more effectively when you move on to treating the algae.
Next, remove as much debris out of the pool as you can. This typically involves skimming off leaves and anything else floating on the surface of the water, then vacuuming the bottom if there is a lot of buildup.
After that, give the walls, floor, steps, and corners a thorough brushing. Algae can cling to pool surfaces, especially in spots with weaker circulation, so brushing helps break it loose and makes the next treatment more effective.
And as tempting as it can be, try not to skip the areas around ladders, returns, or steps, as they’re easy places for algae to hang on.
Now it’s time to raise the chlorine high enough to kill the algae.
How high you need to go depends on your stabilizer level, since cyanuric acid (CYA) affects how active the chlorine is. Use your CYA reading to determine the proper treatment level, then add enough liquid chlorine or pool shock to reach it. Avoid using more stabilized chlorine if your CYA is already high, though, since that can make the problem harder to manage.
As the pool clears, test the chlorine again and add more as needed to keep it at the treatment level. If it drops quickly, it usually means the algae and other contaminants are still using up the chlorine. So, keep treating until the algae is gone and the chlorine starts holding more consistently.
Once the algae starts dying off, the filter needs to remove all of that material from the water. Keep the pump running continuously while the pool is clearing to keep the water moving through the filtration system.
And watch the filter pressure as you go. If you notice it rises about 20 to 25% above the normal clean pressure, take a minute to backwash or clean the filter before continuing. You may need to do this more than once if the pool was especially green.
Note that the water can stay cloudy for a while even after the algae dies, so don’t shut the system down too early. Keep filtering until the water is clear and you can see the bottom of the pool again.
You may need to replace some of the water when certain levels are just too high to bring back down with normal treatment. That can include stabilizer, calcium, salt, metals, or total dissolved solids.
In those cases, a partial drain can dilute the water and bring those levels back into a more manageable range. You can fully drain the pool if you want, but that’s usually only necessary when a partial drain will not solve the problem, or there’s yet another issue to address.
Most green pools can be cleared without draining, but there are cases where the water needs more than a standard treatment. The key is knowing what is actually causing the problem before you start replacing water unnecessarily.
And if you have already tried to get the pool back under control without much luck, you don’t have to keep guessing. Contact Clark Pools & Spas for help with water testing and treatment guidance, and let us help you figure out what it will take to get the pool clear again.
