How to Clean a Green Above Ground Pool

If you are an above ground swimming pool owner, you may end up with green algae.  Green algae can occur if the sanitizer drops too low, if the filter is dirty or from not running the circulation pump long enough.  It could be from one, or a combination of, these things.  So what do we do about it if our pool turns green.


We need to start with a clean filter.  I know it sounds crazy because we will also be cleaning the filter when we are done.  If you have a small filter for your pool, you may need to clean it multiple times.  This is where the algae is going to get captured, so we need to make certain that the filter has enough room to capture it.

Pump Run Time

When doing an algae treatment, the circulation pump needs to run for 24 hours.  Possibly longer.  If you are using the circulation pump that came with an inflatable above ground pool, these are often undersized so you may already be running your pool pump 24 hours a day.  Every pool is different.  They differ in size, shape, depth and equipment.  We love the BLACK + DECKER Above Ground Variable Speed Pump. It not only keeps your pool water sparkly clean, but it's energy efficient and will save you money on your energy bills.


The very first thing we have to do after ensuring a clean filter, is to thoroughly brush our above ground pools.  We need to brush the walls and bottom of our pools.  This will get the algae free floating and more susceptible to our algae treatment.  Looking for a good pool brush that even does corners and is gentle enough for above ground pools? Try the Ultra-Soft 360-Degree Pool Brush. The more thorough you brush, the better chance you have of your algae treatment being a success.


This may not be an option for some above ground pools since they don’t all have a skimmer.  There are manual and battery powered vacuums available.  If you DO have a skimmer, hook up your vacuum hose and connect your vacuum head to your telescopic pool pole and plug the hose into the skimmer.  Vacuum up any dirt and debris and algae that you can.  This is when your filter may need an intermediate cleaning as it may get full.  I find it easier to invest in an automatic robotic pool cleaner.  Did you know that they make robotic cleaners for above ground swimming pools?  Yes, sir, Bob.  This is a good way to have your pool water sparkling every single day, not just on the day you do your regular pool cleaning.  This one is heavy duty, yet affordable.


The chemicals work more efficiently with a balanced pH, but even if yours isn’t balanced, the algae treatment should still work.  You’ll want to pair a good algaecide with your chlorine.  I really like Yellowtreat.  Yellow Treat is for yellow and green algae, so don’t let the name fool you.  This particular algaecide works with the chlorine we are going to add to break the cell wall of the algae molecules.  You will need 1-3 capfuls, depending on how many gallons your above ground swimming pool is.  As with any chemical, always follow the product’s manufacturer instructions.

Next, we add liquid chlorine.  This type of chlorine is already dissolved and won’t sit on the bottom of your above ground pool like a granular would.  My rule of thumb is 2 gallons per 10,000 gallons of pool water.  We are going to nuke the pool.  

Pro Tip:  Never let anyone swim during an algae treatment.

As I previously mentioned, add the algaecide and the chlorine at the same time.  We need high chlorine levels to shock the pool.  Let the pool circulate for 24 hours.

Vacuum (Again) 

The next day you may want to vacuum the dead algae off the bottom of your swimming pool, making sure your filter is clean enough to handle it.

Clean the Filter

Once the pool is back to blue, we will want to do our final filter clean.  If you have a sand filter, backwashing is fine.  If you have a cartridge filter, you may want to consider just replacing it.

Test the Water

It is not fair to assume that the chlorine will be high.  It may very well be.  Or, all the chlorine got used because the chlorine demand was high.  Check your other fields such as pH and alkalinity.

Balance the Water

After testing, add the necessary chemicals to get your fields back into balance.  Again, following the product instructions.  We need to give adequate time in between each chemical addition while also allowing the pump to run an adequate amount of time after adding a chemical.  Hopefully this worked for you!  Hopefully you were able to identify exactly how it got green in the first place so you won’t have to go through this again.  See you poolside!

Related articles:

Sand in Your Pool? Here’s Why—And How to Fix It

How to Properly Chlorinate Your Pool—In Three Easy Steps

The Safest Way to Store Your Above-Ground Pool for the Winter—Fast