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Algae Treatment

__ Actual Algae: Green or Dark Green

__ Actual Bacteria:  Black, Blue/Green, or Mustard

For Pink, White, or Clear “Algae”, see Pool Tips™ on Bioslime.

Pool Size:                                               gallons 

Sanitizer System:  __ Chlorine  __ Baquacil   __ Softswim   __Bromine    __ Other ____________


1.   Test sanitizer and pH levels.  Adjust the sanitizer to normal levels, and the pH to normal (7.2 to 7.6) or high (8.0), depending on your decision in step two __________________________________.  Vacuum or scoop all debris from pool bottom.

2.   If you can see the bottom of the pool, skip to step four.  If you cannot see the bottom, remove most of the live algae by floccing the pool.  However, do this very quickly, because you are not killing the algae until you finish floccing.


To floc the pool and remove most of the algae:

Note:  quaternary algaecides will interfere with the floccing action at high levels.  Polyquats interfere at very high levels.  If you have already added a large amount of algaecide, the floc may not work.  That’s why we like to floc first.  If you need to add algaecide before trying the floc, use an elemental copper algaecide.

3A. Raise the water level to three inches higher than normal.  You are going to be losing three inches in a few days.

3B. Raise the pH to 8.0, and Total Alkalinity above 130 ppm:                                             .

3C. Floc the pool: (Baquacil Flocculant at 1 bottle/10k, Target Floc Alot at 1 bottle/15k, BioGuard Power Floc at 1 bottle/20k).  Mix it into several buckets of pool water and spread it out over the entire surface of the pool while the filter is running.

3D. Immediately brush the walls while running the filter to circulate the floc and get the algae on the walls into the water so the floc can force it to the bottom.

3E. Continue running the filter about an hour after you add the floc, then shut off the filter, and wait 24-72 hours.  Do not use the pool.  Give everything time to settle.  Test pH every day, and raise it if it drops below 7.5. You’ll know when you’re done.  It should take one to three days, if you really did test the pH daily.  The water should be clear, with white or green stuff on the bottom.  If it doesn’t work, call us.

3F. Vacuum on waste (not on backwash) and not through the tank.  You’ll lose two or three inches of water.  If you are not sure how, ask us.  Then go back to filtering 24/7.

3G. Check the pH and readjust to normal (7.2 – 7.6).


4.   Now immediately kill the algae.  If you wait too long, the algae may grow out of control.  Re-test the pH if necessary and adjust to a normal level.  Add a normal dose of shock to the pool: _____________________________________________ (Target Super Shock at 1 gallon/15K, Baquacil Oxidizer at 1 gallon/10K, Bioguard Burn Out at 2 pounds/12K)

5A. For actual green or dark green algae immediately thereafter, add an initial dose of algaecide: ________________________________________________________________ (Target Algae Bomb, at 1 bottle/20K, Baquacil Performance Algaecide at 1 bottle/20K, or Bioguard Banish at 1 bottle/20K).  Remember, never mix chemicals together.  Add them separately to the pool.


5B. For actual black, blue/green, or mustard/yellow bacteria:  Immediately thereafter, add an initial dose of treatment:  _________________________________________ (Target Yellow & Black Treatment at 1 bottle/20K, Baquacil Premium at 1 bottle/10K, or Bioguard Banish at 1 bottle/20K).  Remember, never mix chemicals together.  Add them separately to the pool.

6. Brush the walls and floor well, to break up the algae and to allow the poison (the shock and algaecide or treatment) to come into contact with all of the algae.  For black or mustard algae, brush hard – their roots are actually inside your pool’s finish.  If you have a plaster finish, use a stainless steel brush – it will get into the pores better.  If you have a vinyl or painted finish, don’t use stainless – it will ruin the finish!  If you have black algae, brush every day for a week.

7.  Filter 24 hours a day until the water clears.  If it does not clear in 4-6 days, add a clarifier, or ask us for a water clarity treatment.  If you can not see the bottom of the shallow end, you may need to floc now.  Read Pool Tips™ for Cloudy Water for ideas.

8.  Return to your normal 3-step chemical usage (sanitizer-shock-algaecide) in whatever method you normally use.

9.  If you have mustard or black algae (actually bacteria), and it returns one to three weeks after following this treatment, treat it the second time, with Target Yellow & Black Treatment (a chlorine enhancer) and a double dose of Target Super Shock.  Follow the directions carefully on the Yellow & Black Treatment.  Most important, brush well to destroy the roots.  These chemicals are not compatible with Baquacil, but we’ve never seen mustard algae in a Baquacil pool.

Revised:  9/6/12

Please let us help you, anytime.

Pool Size: ___________ Gallons Technician: ___________
Date: ________________

Reprinted from Seasonal News, Volume 19, No. 2, August 2011 

Got algae? Generally, that’s because you did not keep up with your chemistry.  However it could also be because of fertilizers in your water: nitrates, nitrites, or phosphates. If you think that might be the problem, ask us for a test.

To chemistry: your chlorine and algaecide has to always be in the water, and your pH has to be right for the chlorine to work.  That’s why Baquacil users rarely get algae.  People who only use algaecide when they get algae actually don’t save any money: it takes more to kill it than it does to prevent it.  Even worse, we only get three beautiful days a summer!  Why would you take a chance on missing two of them while you fought an algae bloom?  You know, you mostly get algae when it’s hot out.

Whether curing or preventing algae, make sure you use the best tool for the job.  First, green algae is a plant that lives on chlorophyll, and it’s actually an algae.  There are more than 7,000 different species in existence, and they are killed most readily by the three common algaecide types: Quat, Copper, and Polyquat.  If you want to know more, ask us, or come to our chemistry class.

“Black Algae” is not really algae – it’s an aquatic photosynthetic bacteria called cyanobacteria that is closely related to “Pink Algae”, “Pink Slime”, or “Red Tide”.  These growths are difficult to treat. Actual algaecides are not much help, though most stores will sell the appropriate treatment in their Algaecide Department because our customers think they have algae.

“Mustard Algae” is a third growth that is much like “Black Algae” and also requires a chemical that’s not really an algaecide.  Generally, the same product treats the “yellow” and the “black”.  The take-away here is to use the right product for the job. Use yellow, mustard, or black “algaecides” for those colors, and use real algaecide for the green stuff. They are not the same.  So be careful!  If someone is selling you a Black Algaecide or a Mustard Algae for green algae, they are either giving you the wrong algaecide, or the algaecide is right and the label is wrong.

Most important, ask for help and follow our Pool Tips™ for Algae.  Following the right order is ten times more important than how much money you spend. Doing it right the first time is faster and cheaper than doing it wrong four times.


We write Pool Tips for the exclusive use of our own local customers. They are meant as a summary of general information, to be discussed in our store, with our staff, to determine which items are best for specific pools. Pool Tips are a trademark of Gull Group, Inc. All rights reserved.

Our suggestions assume that you have given us a proper description of your pool’s size, history and symptoms. Sometimes we can figure it out, sometimes we can’t. Your doctor has years more training, far better diagnostic tools, and makes way more money—and sometimes he or she gets it wrong, too.

  1. Read all labels carefully, and only use chemicals exactly as described on the label. Never mix chemicals together outside of the pool. Some of them can cause a fire or explosion.
  2. Do Not follow any advice or suggestions here without coming into the store, customizing them to your specifics, and receiving them in writing.
  3. Do Not print these out or reproduce for any purpose whatever. They are all copyrighted, and we take our copyrights very seriously.
  4. Don’t Blame Us for anything. It’s free advice, and worth the price paid. We’re trying to help, but pools are complex, and chemicals and electricity are dangerous.
  5. Our Best Advice: Go find a local pool dealer who knows what they are doing, become a steady customer, and give them a chance to learn about you and your pool. Pick a brand, pick a store, and stay with them.