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Thread: Black algae

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    Join Date
    Jul 2015
    Carmel, IN

    Black algae

    We have a 35,000 gallon, in-ground vinyl pool. Last week, water was beautiful, all chemicals perfect, then black spots became evident in the deep end of pool. These spots aren't huge, but they don't respond to brushing at all. Went to pool store ---they said it was probably black algae. Bought algaecide, followed directions, upped FC, brushed, waited. Zero results. Did entire process again---algaecide, shock, brush, backwash, etc. still no results! Any ideas? We are leaving town for two weeks and I'm terrified of returning to a "black hole"!!!
    35,000 gallon, vinyl in-ground pool

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    TFP Guide

    Azgirl71's Avatar
    Join Date
    Apr 2015
    Sierra Vista, Az

    Re: Black algae

    Welcome to TFP! I am sorry you have this issue with your pool.

    Let me ask first off do you have a recommended test kit?

    I encourage you to read through pool school. There is a lot of great information there.
    Start with the ABC's of pool water chemistry.

    Can you take a pic and upload it to photobucket, then copy the IMG code and past it here. Pictures help us help you
    Intex AG vinyl 15' x 48" 4,300 gallons due to skimmer install, Krystal Clear SF pump combo 2800 GPH, Krystal Clear SWG, Pool Blaster Max vacuum, Hayward thru the wall skimmer, TF 100 test kit with speed stir, K 1766 Taylor salt test, My SLAM Process

  3. Back To Top    #3

    Join Date
    May 2015
    Las Cruces, NM

    Re: Black algae

    you have to open up the black heads so chlorine can kill them.
    15,000 IG Plaster Triton II TR100 Sand Filter Has a gas heater but not using it.
    MAX-FLO VS SP2302VSP 1970's pool Taylor K-2006 FAS-DPD
    1 skimmer and two 'main drains' via reverse plumbed caretaker lines. -Someone incapacited the real main drain.

  4. Back To Top    #4
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Black algae

    Welcome to TFP!!!

    You need to definitively identify the spots before you know how to proceed. Can you scrape them off with a fingernail? If so, if you spread it on some paper is it green?

    It is pretty rare for black algae to just appear in a pool unless it is very neglected.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  5. Back To Top    #5
    Patrick_B's Avatar
    Join Date
    Jun 2011
    Midland TX

    Re: Black algae

    I can't add much to the advice given thus far, so I just wanted to say welcome to TFP.
    TFP Moderator
    Essential Links:
    ABC's Of Pool Chemistry, Test Kits, SLAM Your Pool
    28K Gal IG FreeForm, CLI Quartz, Pentair 36"SF & VS Pump, Dolphin M5, Rheem

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