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Thread: Green stains on bottom of gunnite pool....

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    Green stains on bottom of gunnite pool....

    I have a 35,000 gal gunnite pool and upon opening the pool, the water was really green. After a week or so of trying to clear it up, my pump died and also realized that my filter was pushing DE into my pool through the return lines. I decided to replace all of my equipment 2 weeks ago and bought a new 2HP Super Pump, a Hayward DE6020 Pro-Grid 60-Square-Foot Vertical D.E. Filter and a new multiport valve. Once all new equipment was installed, the water cleared up in about a day but I quickly realized I had a 1/4 inch layer of DE powder covering the entire pool floor. I manually vacuumed to waste to remove DE and noticed pool floor was REALLY green. I proceeded over the next few days to brush ( I use a metal brush)the pool everyday to remove the algae but there are now very large areas of green that will not come off (see video)

    I have shocked the pool numerous times and have also used a Anthony Slyvan Green algecide remover, but it does not remove the green staining.
    25k gallon, inground, vinyl, with sand filter

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    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Green stains on bottom of gunnite pool....

    Lay a chlorine puck on a stain for a few minutes. If it leaves a clean circle, you have organic stains, and maintaining FC at the high end of normal should bleach it out in a few weeks.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Green stains on bottom of gunnite pool....

    Welcome to TFP!

    I suggest getting a sock, putting some dry acid in the sock, and placing it on a stained area for a couple of minutes. You can also try placing a trichlor tablet on a stain for a couple of minutes. If the trichlor works better then they are organic stains. If the dry acid works better then they are copper stains. If neither works well we need to investigate other possibilities.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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