How to Clean Algae From Your Swimming Pool

Algae.  We have all had it at some point or another.  By the time we can see viable algae, it has been going on for days.  So if your pool walls ever feel slimy, that is actually the beginning of an algae bloom.  There are thousands of varieties of algae, but to keep things simple, we typically break it down to green, yellow and black.  No matter what color it is, we obviously want to get rid of it.

How to Get Rid of it

Good news.  You can be rid of this green (or yellow) monster with a few simple steps.

  1. Disconnect the automatic pool cleaner (if you have one), but leave it in the pool.
  2. Run the pump 24/7 (the pump needs to stay on the entire process)
  3. Brush the entire pool
  4. Add x pounds of Calcium Hypochlorite. This depends on the size of the pool.  Typically 2 pounds per 10,000 gallons of water. (For un-painted, plaster pools only)
  • Or x gallons of liquid chlorine. (For all pool types.)
  1. Add x ounces of algaecide poured directly into the pool.  (Dosing depends on the size of the pool and the manufacturer’s instructions found on the product label)
  2. Run the pump/filter for 24 consecutive hours

The Next Day

  1. Clean the filter.  Recharge with DE if that is your filter type.  If the filter was just cleaned, backwash the filter and add DE.
  2. Add x pounds of Calcium Hypochlorite again (unpainted plaster pools only)
  • OR x amount of Liquid chlorine (all pool types) Run the pump at least 2 hours.
  1. Perform a phosphate treatment as needed
  2. Use a clarifier or enzyme as needed to remove dead algae too small for the filter to filter out.

Cloudy Water

A lot of times after an algae treatment, you water can become cloudy or hazy.  This could be because there is no sanitizer.  You may be thinking. “Wait!  I just added a ton of chlorine.”  Sometimes we add just enough to kill the algae and there is nothing left.  So we may need a 3rd shock.  

The other reason is that dead algae particles are microscopic.  They may be too small for your filter to filter out.  Especially if you have a cartridge filter.  In this case, you will want to use a clarifier that either “eats” the algae away or one that “clumps” the algae together into larger pieces that your filter can now grab.

Clumps of Algae

Sometimes there will be large or small clumps of algae floating in the pool.  These you will want to vacuum out.  You may find it helpful to use a flocculant, like Alum, to clump it all together and drop it to the bottom.  Then you can vacuum it out either by letting your automatic pool cleaner do it if it is minor, or use your manual vacuum to vacuum to waste (if you have this option) or just into the filter.  Either way a filter clean is needed after an algae treatment.  

Filter Clean

You may not want to hear this, but sometimes we have to clean our filter twice when battling the green monster.  If your filter is full of algae before treatment, you will have to clean it so that there is room to catch the algae.  You 100% HAVE to clean the filter after an algae treatment.  If we do not clean the filter to rid the algae, then all we have really done is relocate it.  It will be back blooming away in no time.


Since algae eats phosphates, oftentimes when we kill the algae , the phosphates they haven’t digested get released into the water.  Gross, huh?  Check your phosphates after an algae clean to determine if one is needed.  


The product you purchased to use during your algae treatment may have a maintenance dose for weekly or monthly treatment.  Follow the product label’s instructions.  Keep in mind an algaecide is like a flu shot.  It won’t keep you from getting algae, but will make an outbreak less severe.

I hope this helped answer your questions about how to clean algae from your pool.  Proper chemistry and circulation will be key in preventing a bloom…no matter the color.  See you poolside!