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Thread: Black Algae and dying pump

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    Black Algae and dying pump

    Howdy! I've been lurking off and on for a while, and up till now I've always found the answers I was looking for without needing to post. No such luck with this one, though, so here goes:

    About four or five days ago, I started noticing what has to be black algae on the wall of my in ground pool around the light fixture. I have a basic idea of what to do about it, but unfortunately, I'm pretty sure my pool pump is about to die. The noise level has been increasing for a few weeks, and it's just about intolerable now, and I've just flipped it off (taking the SWG with it, of course). I'm likely going to have to replace it, but that will take a few days, at a minimum, and I'm not sure what to do about the algae in the interim. (It's fairly small right now, maybe 3 inches by 8 inches or so).

    I have a Blue Diamond pool robot that I was going to use to filter the water until the pump is operational. Can I try tackling the algae problem while that is my main water filtration system? I don't want to damage it with higher chlorine levels or something like that, or waste my time if it's not up to the task.

    Thanks for any advice!
    19K kidney-shaped gunite; Hayward FNS Plus 36 sq. foot DE filter; Pentair 1 HP pump; Aquarite SWG; Orlando, FL

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    Join Date
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    Re: Black Algae and dying pump

    Sometimes they start to make noise if theres a clog, acrorn bits etc.
    Is there alot of air in pump basket?
    Try opening pump and use a copper ground wire to get crud out.
    Is robot suction or return?

    I know algeacide is not liked here but would this be an exception? guys?

    ps is filter size in your sig correct?
    25k I/G ecostar ccplus Polaris plaster

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    Re: Black Algae and dying pump

    Whoops, off by a factor of 12 there on the pool filter. Thanks for the catch!

    There's not a lot of air in the basket now, but I had a leak (fixed a few weeks back) and for a while I was running a lot of air through there when the water level got too low. I suspect that is what caused my pump to become so noisy now. Still, it's worth checking for crud, so I will. Thanks.

    As for the robot, it's self contained -- no hoses running to it from either the skimmer or the return.
    19K kidney-shaped gunite; Hayward FNS Plus 36 sq. foot DE filter; Pentair 1 HP pump; Aquarite SWG; Orlando, FL

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    Re: Black Algae and dying pump

    Quote Originally Posted by Hogtown
    About four or five days ago, I started noticing what has to be black algae on the wall of my in ground pool around the light fixture.
    If the black is only around the light fixture, then I would suspect that it might be related to the light. Perhaps corrosion of metal, or something in the niche. Has your chlorine been low enough for algae to form? (Less than 7.5 % of the CYA?).

    If it is algae, you can go to shock level using liquid chlorine and mix it in by thoroughly brushing the entire pool.

    A picture would help if you could post one.

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    UnderWaterVanya's Avatar
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    Re: Black Algae and dying pump

    Agree with above - bleach to shock level, pull light, scrub behind it, brush pool, put light back (if it will entangle robot), run robot, repeat.
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

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    Re: Black Algae and dying pump

    Can't get a pic quite yet, but I just ran the numbers:

    FC 6.0
    CC 0.0
    TC 6.0
    pH 7.6
    T/A 45
    CH 300
    CYA 50

    That's this morning, with the pump and SWG only running for a short period -- an hour maybe -- yesterday. Alkalinity has never been that low before, for whatever that's worth.

    Will try to post a picture after church. And thanks again for the help!
    19K kidney-shaped gunite; Hayward FNS Plus 36 sq. foot DE filter; Pentair 1 HP pump; Aquarite SWG; Orlando, FL

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    Re: Black Algae and dying pump

    The current FC is sufficient. However, if the FC was previously too low, then it might be algae. If the FC has not been less than 7.5 % of the CYA, then that would make algae less likely.

    Your overall numbers are too low for a plaster pool. I would raise the TA up to about 60 or 70 ppm, allow the pH to go up to about 7.7 or 7.8, and raise the Calcium to about 350.

    What is the water temperature?

    How old is the plaster and what is the general condition of the plaster?

    Is the black mainly around the light screw?

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    BoDarville's Avatar
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    Re: Black Algae and dying pump

    Hogtown:

    Agree with what many others have said about going through the shock process and cleaning behind the light fixtures and any other nooks/crannies where algae can gain a foothold due to reduced circulation in those areas. Also would brush the pool since your pump's operation appears to be impaired. Algaecide is of little to no value on an existing algae bloom, so I wouldn't bother using that.

    As for the circulation, the best remedy is to repair or replace the pump ASAP. Until that happens, here are a couple of options that can be used on a temporary basis:
    • If you have another portable pump of some sort, you can try using that to recirculate the water. True, it will not be filtered but it will provide some water movement which is better than nothing.

    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
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