How to Clean a Green Pool in 24 Hours

Inevitably, most swimming pool owners at some point in life will find themselves with a green swimming pool.  This is an algae bloom that got out of hand.  Don’t panic!  Don’t drain the pool!  Let’s talk first about how it may have gotten green and then what to do to clear it up.

How a Pool Can Turn Green

There are several ways a swimming pool can turn green.  You may have one, or a combination of the following.  Low/No sanitizer.  We need to always maintain a sanitizer level of 2-5 ppm (parts per million).  If yours drops below this, not only are you susceptible to algae, but the water is unsafe for swimmers.  Having a balanced pH, ideally a 7.5 ppm, allows our sanitizer to work most efficiently.

Poor circulation is another way.  This can be from not running your swimming pool pump long enough to create what is known as a turnover. A turnover is when the amount of water equal to the amount of water in the pool passes through the filter.  Running your pump at night can also cause algae.  This is because the chemicals only mix and work when the water is moving.  When do we need our chemicals the most?  During the hottest part of the day.  If you are skimping on the hours your pool pump is on or running it at night, it is probably because you are trying to save money.  The best way to save money AND have a clear swimming pool is to invest in an energy efficient, variable speed pool pump.  Check out these American made bad boys here Homeowners who switched from an old fashioned single speed pump to a variable speed pump claim a savings, on average, of $70 per month!  Of course, this varies per region.  

Part of circulation is having a clean pool filter.  When your filter gets to be 8-10 psi (pounds per square inch) it needs to be cleaned.  You can always backwash if you have that option, although you should do a full filter clean approximately every 6 months if you have a cartridge or diatomaceous earth filter.  Every 2-3 years if you have a sand filter.

Let’s talk briefly about phosphates.  Phosphates are anything organic: leaves, flowers, pollen, etc turn into phosphates.  Guess what algae eats?  If you guessed phosphates…you would be correct!  Phosphates are only a problem when they are a problem.  For example if you start to get an algae bloom and have a Las Vegas Buffet laid out for the algae, you just might end up with a green poo.

There is a Solution!

When dealing with a green pool you’ll first want to balance the pH.  As we chatted about previously, this allows the chemicals to work more efficiently.  Next you’ll want to brush the pool thoroughly.  The walls, floors and corners.  Need a good brush to do this?  I like the 360 degree technology of these brushes.  And they also do corners without needing to switch to a different brush.  After you have brushed the swimming pool you need to turn on the equipment.  The pump needs to run the entire 24 hours.  If you own an automatic pool cleaner, leave it in the pool disconnected to that it can get treated as well.

You will need to add copious amounts of chlorine paired with an algaecide to combat the green monster.  For inground pools I recommend using calcium hypochlorite.  If you have a salt pool or another kind of special vessel, I suggest liquid chlorine.  I say use 1 pound per 10,000 gallons of pool water.  1 gallon of liquid per 10,000 gallons as well.  Add this in conjunction with your algaecide.  I am a big fan of a product called Yellowtrine, which is sodium bromide based and works on yellow and green algae.  2-3 capfuls depending on the size of your pool.  This algaecide works with  the chlorine to break down the algae on a cellular level.  Let the pump run overnight.

The next day you will add another dose of chlorine that you used the day before.  For instance, if you have a 20,000 gallon pool and used 2 pounds of calcium hypochlorite with the algaecide, put in another 2 pounds.   This is to reestablish your chlorine reserve so we don’t end up in this boat again.  Test the water and balance any needed fields.  I would take this opportunity to net out any leaves and other debris so our pool will really be clean.  Here is a cool cleaning bundle. 

Now that all the algae is dead, it has moved to your swimming pool filter.  Time to throw the baby out with the bathwater.  We need to do a full filter clean.  Again, if you have a sand filter, just backwash.  You may find that your water is cloudy.  This is dead algae particles that are too small for your filter to pick up.  Once the chlorine level is 5 ppm or below, you can add a clarifier.  I recommend Natural Chemistry’s Pool First Aid as it is designed for after an algae treatment.  Instead of clumping everything together, causing you to have to vacuum, it actually eats the particles away.

Now we have a nice, sparkling, blue swimming pool again.  Hopefully we learned something so we don’t have to go through this again.  See you poolside!

Want to know how to clean the bottom of your pool? Click here to read more. Do you have trouble cleaning the white water mold out of your pool? Click here to read more.