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Thread: Black Algae in Saltwater Pool

  1. #1
    sb2323 is offline ** No working email address ** sb2323 0
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    Default Black Algae in Saltwater Pool

    Hi, thanks for any advice. We have a saltwater pool that had developed black algae. Is the treatment the same as for a chlorinated pool? Also, I have read that a great deal of scrubbing is required before the chemicals can work. Is a wire brush on the end of a pole ok or do I need to get into the pool and scrub it hard by hand? (I am a woman, not sure if I can scrub hard enough using the pole.) Will shocking the pool be beneficial even if I haven't been able to scrub it yet? And can I use regular bleach instead of shock treatment? Do I need algae treatment too? Any specific product recommendations would be much appreciated. I am planning to scrub it down 2-3x daily, double shock daily. How often do I need to clean the filters / backwash during this process, and should I replace the sand? Also, will swimming in the pool and/or using the heater during this process seriously hamper the recovery? Our daily swim is the highlight of my young children's day. :-(

    TIA for any help.

    Susan

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    Default Re: Black Algae in Saltwater Pool

    I would raise your chlorine levels to 12PPM FC and run your filter 24x7 backwashing every few days until the algae bloom is cleared up. You can also add Polyquat 60% to assist with the clean up. The best price I've seen on Polyquat is from Leslies Pool Supplies and it's called Pooltrine.

    http://www.lesliespool.com/shopping/...word=pooltrine

    Physically getting into the pool with an adequate wall brush will be necessary to completely remove the bloom. Once you've had an algae bloom you will have to be diligent about keeping it at bay or it will return.

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  3. #3
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    Default Re: Black Algae in Saltwater Pool

    Quote Originally Posted by sb2323
    We have a saltwater pool that had developed black algae. Is the treatment the same as for a chlorinated pool? Also, I have read that a great deal of scrubbing is required before the chemicals can work. Is a wire brush on the end of a pole ok or do I need to get into the pool and scrub it hard by hand? (I am a woman, not sure if I can scrub hard enough using the pole.) Will shocking the pool be beneficial even if I haven't been able to scrub it yet? And can I use regular bleach instead of shock treatment? Do I need algae treatment too? Any specific product recommendations would be much appreciated. I am planning to scrub it down 2-3x daily, double shock daily. How often do I need to clean the filters / backwash during this process, and should I replace the sand? Also, will swimming in the pool and/or using the heater during this process seriously hamper the recovery?
    As far as I know, the salt doesn't affect the black algae one way or the other.

    As far as brushing . . . it's important, but persistence is more important than strength. I've seen folks attack it, as if one really, really hard scrubbing would get it all cleaned up. No such luck! If you want to get rid of black algae after it's become established, you have to commit to approaching it as a long term problem. Think weeks, not days.

    (Of course, many pool stores will be happy to sell you any number of products that promise quick results. And, they'll also be happy to explain -- when you don't get quick results -- why it didn't work for *you*)

    What's important is brushing enough to remove any dead top layer, or at least to scratch it, and expose the live algae to the chemicals in the pool. But it's much more important to brush some today, and the day after and the day after that, than to brush really, really hard today.

    Another thing you need to keep in mind: black algae doesn't grow rapidly, and didn't appear in your pool suddenly. It's there because, day after day, the chemical levels weren't right. And, once it's gotten a start, it's unlikely you will EVER get rid of all the roots and spores penetrating into your pool. (I'm assuming it's NOT a vinyl or FG pool??) So, even if you 'get rid of it' for now, it will come right back unless you learn to maintain proper chemistry day after day in the future.

    Now, you didn't post test results, or tell how you've been treating your pool, so I don't really know what you've done wrong. There are numerous possibilities; here are a few of the more common:
    • Low, or inconsistent, chlorination.
    • High pH, not compensated for with higher chlorine.
    • High stabilizer, not compensated for with higher chlorine.
    • Poor circulation, or not running the pumps enough.
    • Porous or damaged plaster, not compensated for with higher chlorine.
    Keep in mind that a single day -- or even week -- of one of these problems wouldn't lead to black algae. It just doesn't grow that fast.

    So, what you really need to first, is figure out what's been going wrong, and learn how to correct that. Otherwise, anything you do to get rid of the algae will be only very temporary in effect! Fortunately, as many PoolForum members can tell you, doing it right is easier and cheaper than doing it wrong, once you learn how!

    Meanwhile, except for the trip and fall hazard from the black algae, there's no reason to not use the pool while you work on the problem . . . as long as you have chemistry that's adequate for sanitation

    Once you figure out what you need to correct, and take care of that, the solution is pretty straight forward:
    • Brush regularly.
    • Maintain chlorine levels 50% higher than you'd otherwise need to maintain.
    Using polyquat will help some, especially if you can FREQUENTLY brush hard. But, it's still going to take weeks, as a rule, not days.

    Best wishes,

    Ben
    "PoolDoc"
    Last edited by PoolDoc; 04-25-2006 at 04:23 PM.

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    sb2323 is offline ** No working email address ** sb2323 0
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    Default Re: Black Algae in Saltwater Pool

    Thank you for your replies. I have done, and will continue to do, as you suggest. It has noticeably cleared up. You are right--it is our fault that we got in this situation. Didn't maintain the proper level of chlorine then heated the pool for a couple weeks for early-season swims. Now we're paying the price, and have learned our lesson. :-/ I really appreciate your detailed responses on how to correct it.

    This is our first saltwater pool and we're not really sure how to maintain it properly. The previous owner just told us to dump some salt in it when the readings were low and to backwash/clean the filters. We haven't been testing any chemical levels at all, other than looking at the readings on the control panel. I looked at the manuals but they were no help. I will look around the internet and see if I can find some good basic info on what all should be done on a regular basis.

    Susan

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    Default Re: Black Algae in Saltwater Pool

    All the basic info you might need can be found by reading through the forum and the sister website www.poolsolutions.com! There is a lot of misinformation on the net and you have to be careful! The info here and on poolsolutions is sound and easy! If you have any questions just post in the appropriate areas of the forum and you will get all the help that you need!
    11.75'x23.75' kidney 6.5K gal IG fiberglass pool/300 gal acrylic spillover spa combo; Aqualogic automation/SWCG; Pentair Clean and Clear 150 cart filter; 1.5 hp uprated 2 spd Pentair Whisperflo pump; PF:17
    Retired pool store and commercial pool maintenance guy.

  6. #6
    sb2323 is offline ** No working email address ** sb2323 0
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    Default UPDATE: Black Algae in Saltwater Pool

    Thank you again for your helpful advice. After a couple of weeks of faithful scrubbing and superchlorinating every day, we kept noticing new outbreaks of the algae. :-( Took a water sample to the local pool store and our salt tested at 6100, but chlorine was 0. Oops! Our salt display had consistently read 0 for a couple weeks. From that, we figured out that the AquaTech cell was bad, was not reading the salt, and was not producing chlorine. So yesterday we drained half the pool and refilled it, and replaced the cell. In the process DH turned the handle from "waste" to "filter" without turning the filter off and cracked the casing and broke the handle off. :-( So we are unable to run the filter or heater at all till Monday when we can hopefully get the parts replaced, get the water properly balanced, and get the black algae under control once and for all.

    Anyway, I was so frustrated with the black algae situation that I did buy some algaecide at Leslie's and it surprisingly worked quite well. The instructions were very vague, but this is what we did. As I mentioned we had already been scrubbing hard and faithfully once or twice a day. We gave it another good, thorough scrubbing and turned off the filter. Then we dilluted the solution and poured it around the perimeter of the pool, and turned on the filter a couple hours later. The next morning when we drained half the pool most of the algae was gone.

    Thanks again for your helpful advice!

  7. #7
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    Default Re: UPDATE: Black Algae in Saltwater Pool

    I don't think anyone has addressed your basic problem. You need to know that all the saltwater system does is produce chlorine. You still have to monitor all the normal pool parameters including Chlorine levels. The only difference is instead of adding chlorine manually you ajust the Saltwater system to regulate you chlorine levels. All other pool parameters need to adjusted with the methods discussed here and at poolsolutions.com. Keep an extra vigilant eye on your PH level it will go up faster with the Saltwater system then with other chlorinating levels.

    Also you will need to use bleach or some other chlorine source to get a high chlorine level in the pool to help kill the algae. Even in "boost" mode the Saltwater system won't produce more then 5-6PPM of chlorine. (at least mine won't)

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