I Have Algae On My Pool Walls. What Should I Do? - How Do I Get Rid of Algae on my Pool Surface?

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, Click HERE!


             If there is "Dead" algae sitting in a green "powder" form on the surface of the pool, 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 Click
HERE! 'FIRST', and follow the instructions there. (Cloudy or Green Water is ALWAYS due to circulation and filtration.)

Assuming you accomplished everything on the start page of this section, these are the f
irst things to Check(If not, Click HERE)

            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 Click HERE! And after you have read that page, go one more level down to the "Chlorine Rinse" page.


          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, I advise that you hire a professional.


          IN CASE YOU WANT TO IGNORE MY ADVICE ON GETTING A PROFESSIONAL, 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 OR AN ACID WASH AFTER A  CHLORINE RINSE. You will create mustard gas. The same substance that they used to kill thousands in World War 1. You, your pets, other family members, neighbors, ... can be severly harmed or even die.)

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 VALLEY SUPPORTS, 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 all the money you will save.


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



        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 Pool Maintenance Chlorine Rinse)

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

        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 the floor, steps or love seat, you can pour granular 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, nor does your pool man. 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. Don’t get it on you, your clothing, or the decking. 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 your cartridge filter elements) Click HERE for Filter Maintenance Instructions.


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


a.) I know that a lot of companies and even the labels themselves, often push for 7.4 pH 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. The scientific research proves this, which is why many chemical companies recommend this. (Plus, it lessens the likelihood of staining for metal based algaecides.) Also, if you look at the research these companies fail to examine, you will find that plants almost all plants, including algae, thrive at the lower pH and lower alkalinity levels, and you are 10 times as likely to grow algae, even at those increased free available chlorine levels you get with the lower pH ranges, than you will get if your pH is at 7.8. Plants love low pH and low alkalinity. (Search on hydroponic research, 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. What I find amazing is that these same pools have algae EVERYWHERE. Once the pH is raised to 7.8, the algae in these pools goes away, without adding ANY other chemicals. Note: If you ignore these facts, and having a 10% increase in free available chlorine, is more important than getting rid of the algae, then lower your pH.  


d.)  Yes, the higher the pH the more of the metal based algaecides may come out of solution(The staining issue previously mentioned), 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 metal based algaecides, I go for a 7.6.


         There are people that say keeping the pH higher might result in more 'staining' or 'scale' build up, are ignoring the astronomically high hardness levels of all the water that comes out of the tap in the Phoenix. The hardness here in Phoenix comes out of the tap always above 650 PPM (2012) in every tap in the valley, and sometimes, in certain places, at certain times. at 1200 PPM or higher. YOU CAN'T PREVENT CALCIUM BUILDUP ON SURFACES AT THESE LEVELS. The ONLY way to control it, and the damage it does, is with regular drains. Follow the manufacturer’s recommendations for every pool built in the last 5 years. If your total hardness exceeds 750, drain and refill your pool at the next available opportunity. Note: Every pool in the Phoenix area, without special treatment, will be. (Note, things that remove hardness from the water below 150 ppm will cause your plaster to crumble off your pool, often adding other chemicals that will stain and discolor it, … the best method, is an annual drain and refill of your pool, and this has been the best method for the last 30 years.


           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. (Again, all metal based algaecides permanently stain 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. (Yes, even if you keep the pH low.) If you have a pebble tech surface, it will be mostly impervious to any staining to any of these products, or the staining will not be noticeable.)  


         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 of algaecide does not appear to be handling your algae problem, switch to another.


        When choosing an algaecide, 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 even at the same price, you are actually getting more “algaecide” in the quart than in the gallon. You are actually getting 20% more algaecide in the quart that you would be getting with the gallon. You can add your own water. Again, follow the manufacturers recommendations, (Except for low pH) and if one type of algaecide 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, ... red men become pink, black become light grey, … and at best everyone swimming will be real uncomfortable.

            5.) Again, if, after a week of brushing at least 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, if you have tried both of those, try a chemical based algaecide(Like Algaecide 60 extra strength). Keep everything else the same(i.e. pH, free Chlorine, …), and keep rotating the different chemicals until all the algae is gone.(If you are having troubles like this though, one thing I can guarantee, you haven’t drained your pool in the last few years.)

          Draining your pool completely, and refilling it, every single year with cartridge filters, and every 2 years with other types, is a requirement. (Still preferably every year.) This is your best protection against MOST pool problems. Risk of algae, scale, staining, filter damage, deposits on tile, chronic algae, customer complaints, ... go up 30% every year you do not drain your pool, 50% every year with a cartridge filter. Don’t you DARE gripe at your pool man about problems if you don’t follow these directions. EVERY manufacturer of pools in the valley says that this is what should be done. Don’t do this, and no matter what the problem, YOU , AND YOU ALONE, are to blame. You need to apologize to your pool man for the problems YOU caused.  


You 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, you are buying the active ingredient(s).






                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.) Again, 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.