Pool Surface Covered in Algae

Pool Surface has Algae


This Page covers having Walls, Steps, Floors ... the actual “Surface” of the pool being  covered in algae.


             If the water itself is green or murky, GO TO:  "Water - Green or Cloudy". (Click HERE)


            If there is "Dead" algae sitting in a green "powder" form on the surface of the pool, GO TO:  "Dirt or Powder on the Pool Floor" (Click HERE)



Note: In all cases, if the water is clear then the problem is not directly related at all to filtration or proper adjustment of water circulation.

If the water is cloudy as well, then please Select the 'GREEN OR CLOUDY WATER'  'FIRST', (Click HERE) and follow the instructions there. (This is ALWAYS due to circulation and filtration.)

Assuming you accomplished everything on the start page, First Things to Check: 

            1.) Has the pool been COMPLETELY drained, refilled and restabilized in the last year (Cartridge Filters) or in the last 2 years for Sand or D.E. Filters?


a.)          If not, and the weather is cool enough (Under 85 Degrees for a Plaster/Marcite Pool, Under 90 Degrees for Pebble Tech Surfaces), drain the pool and do a chlorine rinse (See Pool Maintenance: Chlorine Rinses) you need to completely drain and refill the pool anyway. Do so.


b.)          Then pour pool bleach (which is usually about 2-4 times the concentration of household bleach) over every inch of the pool.


c.)           Wait 15 minutes, high pressure rinse every inch, and repeat on any area still having algae issues until all algae is 100% gone.


d.)          Yes, wear protective clothing, gloves, ... anything that gets any of this bleach on it will get a chemical burn or a hole in it. 


e.)          You have been warned. If you don't have experience with corrosives, chemicals that can gas you and kill you, like mustard gas, and don't want the risk, hire a professional.


f.)  NEVER MIX ANY CHEMICALS(Unless the labels say it is safe to do so). NEVER DO A CHLORINE RINSE AFTER AN ACIDWASH OR AN ACIDWASH AFTER A CHLORINE RINSE. You will create mustard gas, that they used to kill thousands in world wars. You, pets, other family members, neighbors, ... can be severely harmed or DIE.)

 2.) Has the filter been properly backwashed or cleaned. Read the sections on filter maintenance, and follow them.

Note: Yes, we all know someone who supposedly never drained their pool for 6 or 7 years with supposedly no ill effects. I knew a guy who "Supposedly" never did an oil change for 60,000 miles with 'supposedly' no ill effects also. He just replaced his engine. You can avoid doing regular maintenance, if you want. Trust me, you are going to pay triple, or more, for ignoring the draining schedule EVERY POOL MANUFACTURER IN THE VALLEYSUPPORTS, and says should be followed.


        You have been warned by them, and by me. If you aren't going to drain and refill your pool, you should cut back on those oil changes, brake pads, windshield wipers, … dental and medical checkups, ... as I know people who have avoided those for 10 years or more as well. Just look at the money you will save.


        If the algae looks 'BLACK' in color, and usually starts as spots (Kind of like black chicken pox “In Black” on your pool surface), or at the water line on your tile or pool surface. If you see this, you have black algae (Kind of a trade name. It is actually 'Blue/Green Algae' but it is dark enough to be called 'Black'.) This algae is VERY resistant to chlorine unless it is in concentrated and in DIRECT CONTACT with the algae itself. Again, if you haven't drained and refilled your pool according to recommendations, drain it and do a Chlorine rinse. (See Chlorine Rinse) (Click HERE)

Warning: NEVER leave a chlorine tab sitting on a pool surface as it will PERMANENTLY discolor it.

        With the warning out of the way, The Best solution to killing black algae is to 'COLOR' all of the black algae white by scrubbing each spot directly with a chlorine tab. For Algae on flat surfaces, you can pour chlorine 'Shock' or 'Tri-Chlor' directly on the spots (With the equipment off.). 


        One more thing, algae at the water line, or in crevices in a rock waterfall, ... is not a sign of poor maintenance on the part of your pool care professional. These areas, while damp, or wet, do not contain the Chlorine necessary to kill these algae spores. The only solution is to color these areas with the chlorine tabs. And no, I do not include this in my weekly service rates. I usually charge an hours labor to jump into a pool in the summer, swim around, cool off, take a tab out of the chlorinator and scrub every speck of black white. It's a tough job, but someone has to do it. If you do not want to pay me to cool off in your pool, you can do it. Just don't rub your eyes, swimsuit or any other sensitive areas until you thoroughly rinse your hands.


        If you have severe black algae, and just drained your pool, or it is too hot to drain it, add an algaecide like Silvertrine. Yes, there is silver in it. .8% Silver. Yes, there is a decimal point before the 8. This is one of the strongest "Silver Based" algaecides available, and silver is best for controlling Black Algae. Follow the instructions on the bottle, but do not lower your pH below 7.6. (Note: This stuff permanently stains everything it gets on. You have been warned.)


Treating Yellow or Green Algae on Walls or Floor of Pool Chemically 

            1.) Follow the Instructions above under "First things to Check" .


            2.) Make Sure your filter is clean (Backwash or clean elements)


            3.) Get your pH to 7.6 and keep it there.


a.) I know that a lot of companies push for 7.4 or even lower, but algae, and all plants, thrive at lower pH and alkalinities.


b.) Yes, at 7.2 - 7.4, you get a 10% increase in free available chlorine levels. Also, if you do any research, you will find that plants thrive at the lower pH and alkalinity levels, and you are 10 times as likely to grow algae, even at those increased free available chlorine levels. Plants love low pH and low alkalinity.


c.)   I often find pools with chlorine levels so high that the health departments would close them for their high “Free chlorine” levels. Yet these same pools have algae EVERYWHERE. Amazingly, once we raise the pH, and the algae goes away, even without further chemicals. It is your choice though.


d.) Yes, the higher the pH the more of the metal based algaecides may come out of solution, but there is a happy medium. Without the need for algaecides to keep algae out, I like the pH at about 7.8. When adding algaecides, I go for a 7.6. Yes, there are a lot of people that say that this might result in more 'staining' or 'scale' build up. But the hardness here in Phoenix comes out of the tap always above 500 PPM now, and sometimes, in certain places, at 1200 PPM or higher. YOU CAN'T PREVENT CALCIUM BUILDUP ON SURFACES AT THESE LEVELS. Control it with regular drains. No, I do not take responsibility for you following my directions. Follow the manufacturer’s recommendations or take the responsibility yourself and follow what I am sharing. I am just explaining what I do and why.


           4.) Boost your free available chlorine. (Hit the back button on your browser. This was already covered.) or (Click HERE)


            5.) With the equipment still OFF, leave the Chlorine sit on the surface for a minimum of 20 minutes, preferably one hour.


            6.) Brush every inch of the pool, walls, steps, front of steps, floor, love seats ... thoroughly. Preferably with a wire brush.


            7.) If all the algae isn't already dead, or this is a repeat problem issue, copper based algaecides are the best for yellow or green algae. I like Swimtrine plus. It has over 60% copper (Active ingredients) and, for the last few years, has offered the best "bang for the buck". Again, follow the instructions on the bottle, but do not drop the pH below 7.6. (This stuff permanently stains everything it gets on. You have been warned.)



            1.) Follow the Steps Above on: "Treating Yellow or green algae ..."


            2.) Note: If you have a plaster or Marcite pool, most algaecides can, or will, cause surface staining or discoloration, EVEN IF ADDED AS THE MANUFACTURERS SUGGEST. If you have a pebble tech surface, it will be mostly impervious to any staining to any of these products. 


         If you have any other type of Algae, I usually start with copper based or chemical algaecides, as they are cheaper, however, if one type does not appear to be handling your algae problem, switch to another. Always look at the percentage of the ACTIVE INGREDIENT in the algaecide. If a Gallon of Copper based algaecides has 1% Copper, and a quart of another brand has 5% Copper at the same price, you are actually getting 5 times the algaecide in the quart that you would be getting with the gallon. You can add your own water. Again, follow manufacturers recommendations, and if one type does not work, try another.

            3.) Brush every inch of the pool with any discoloration at least twice a day preferably with a wire pool brush. 

            4.) Until every sign of algae is gone, Keep the chlorinator filled to the brim, and keep that free available chlorine at the 'turn black swimsuits white' level. NO SWIMMING UNTIL THE CHLORINE LEVELS DROP! You will get a case of 'itchy skin' like you never had before, probably ruin a swim suit, bleach your hair, everywhere, ... and at best be real uncomfortable.

            5.) If, after a week of brushing TWICE a day, WITH A WIRE BRUSH, and following the rest of these instructions, you still have regular problems with algae, switch off with another type of algaecide, if you used copper to start out with, switch to Silver, or a chemical based algaecide(Algaecide 60 extra strength). Keep everything else the same, and keep rotating the different chemicals until all the algae is gone.

        They do make chemicals to lessen chlorine readings, but these readings should drop naturally over time, (2-3 days) to swimmable levels. Follow the directions on the bottle. Normally, Again, I try to never have a pH below 7.6 as algae loves lower pH and Alkalinity readings. Yes, raising pH above 7.6 "can" cause other problems like pool staining. You have to decide what your major problem is, and choose. Again, draining completely, and refilling every year with cartridge filters, and every 2 years MAX (Still preferably every year.) is your best protection against MOST pool problems. Risk of algae, scale, staining, filter damage, deposits on tile, ... go up 30% every year you do not drain your pool, 50% every year with a cartridge filter. Change your oil, or not. Your choice.  


Get what you pay for


Please be aware that I have gone to pool stores where they sell a gallon of silver algaecide for the same price as a quart of Silvertrine. The percentages of silver on the label were .08. That's only 1/10th of the silver but 4 times the total volume. In other words, they diluted 3/4 of a quart (Approximately) of Silvertrine in 1 gallon of water, and charged you the same amount for 1/4 less Silvertrine, and an additional quart of water. Pay attention to the levels. Same with tabs. look at the percentage of active ingredients and inactive ingredients. A 50 lb. of tabs with 23% chlorine, may be 25% cheaper than a 50 lb. of tabs with 46% chlorine, which may be 25% cheaper than a 50 lb. bucket of tabs at 92%. But in each case, you are getting DOUBLE the amount of what you are paying for only 25% more. (This is a dramatization. There are no tabs at 92%. Just be aware of what you are buying.)






                1.) Have your phosphates tested and add a high quality phosphate remover if needed. Note: The better phosphate removers are usually the more expensive ones. Follow Manufacturer instructions.


                2.) If it is the right time of year, drain the pool and do a chlorine rinse. (Follow the instructions in the section on drains, chlorine rinses and acid washes.) (Click HERE)


                3.) If you still have problems, e-mail me. aawesomeinc@hotmail.com