How Much Shock Do I Need for My Green Pool?

Ask anyone who owns a pool what it’s like to get a pool ready for the summer season, and they can probably tell you about how green pool water can get if you let it sit for a few months. The green color is primarily caused by algae and other microorganisms that thrive in watery environments. One of the best things to do to deal with these uninvited guests is to shock your pool with chlorine to kill off the algae and clear the water. 

How to Shock Your Green Pool

Before your green pool shock treatment, we’ll need to take care of a few things. First, you’ll want to attach a brush to your pool cleaning pole and get to work scrubbing all the algae off the edges and bottom of the pool. The goal here is to get the algae to float free in the water so the chlorine can kill it. 

Next, use the skimmer attachment to skim as many free-floating and visible pieces of algae out of the pool as possible. The more algae you can remove by hand, the less the chlorine will have to kill. Similarly, clear out all of your debris traps and filter screens, as they are going to get full with all the algae that needs to be removed. 

Now that the pool has been cleared of as much algae as possible, it’s time to shock it. It’s recommended that you use 12.5% chlorine. You can use bleach instead, but how much bleach is needed to shock a pool depends on its concentration.

It’s very important to wait until after sunset to shock your pool. This is because UV light causes chlorine to break down very quickly if it isn’t mixed with the water. The high chlorine content and specialty equipment required to make it is one of the reasons why pool shock is expensive, so there’s no point in wasting it by allowing UV light to destroy it before it can do its job. 

For a typical shock of a pool that isn’t green, you’ll want to use one to two gallons of shock per 10,000 gallons of water in your pool, but when algae is involved, we’ll need more. For teal green pools, use double this amount; for dark green pools, use three times this amount; for black green pools, use four times this amount. 

After The Shock

You’ll want to run your filters on high all night and inspect the pool in the morning. If the pool is lighter in color but still green, you’ll want to shock it again. Continue running your filters on high all day before the second shock that night. Once again, keep the filters running all night to help clear out as much algae as possible. 

The goal here is to get your pool looking blue but cloudy the next morning. A cloudy pool is a good thing in this situation! It means that all the algae is dead and floating in the water. Clean all your filter traps and continue running your filters until the pool water clears completely.

It is best practice to wait a minimum of twenty-four hours after shocking your pool before you go for a swim. Because killing algae in a green pool requires so much shock solution, your pH levels may be extremely high. Therefore, it’s highly recommended that you test your pool to make sure your pH levels are as close to 7.5 as possible before going for a dip.

If the level is still too high, wait another day. If, after a day, the pH is still too high, you’ll most likely want to add some alkalinity solution to the pool to bring down the pH.

Final Thoughts

A green pool might be a little gross to look at, but it’s easy to fix. In no time, your pH levels will be in balance, and your water will be the clear blue you can’t wait to jump into.

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