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Thread: cloudy green pool

  1. Back To Top    #1

    cloudy green pool

    I have an approx 31,000-33,000 Guinite pool w/ sand filter that is causing me headaches. I have yet to get it clear after being opened for a month. Last week the pool totally turned green on me. It was never clear since I opened it. However the swamp as my family called it was terrible. I have been using slow jumbo tabs since I opened the pool. IN addition, I have been pooring in a few gallons of Bleach each night for the past week. (The first night after the "greenout" I added 4 bags of shock as well as 3 gallons of bleach).

    My levels are as follows:
    Alk 110
    PH 7.3
    CyA 0
    Harness 100
    Total chlorine 1.6
    Free Chlorine 1.6

    My pool is cloudy and the deep end is still green. I believe I have a lot of dead algea. I called the pool guy who opened my pool and he said that he can not power vac the pool until he can see the bottom of the deep end. It seems like a circular equation here. The pool is not clear because of the algea, but he can't vac the pool until it is clear.

    I have the pool running about 18 hours a day and I have backwashed for a few minutes every other day. The shallow area is clearly much better then last weekend but not good enough. I can only see about 4-5 in the deepend (when I lower the net).

    Any help would be appreciated!!!! I want to use my pool already!

  2. Back To Top    #2

    Join Date
    May 2007
    Houston, Texas, USA
    Sorry you are having trouble. Your Hardness reading, is that total hardness or calcium hardness? Either way, besides the algae, your water is pretty aggressive, and bordering on leeching calcium from the pool surface. This can be resolved by running a higher pH, or a higher calcium, or both. Also, if this is an outdoor pool, you need some cya in there. As far as the algae, at zero cya, super-chlorinate up to about 10 ppm free chlorine or even higher. The problem is, your pool is not going to hold free chlorine very long at all, without cya, and with algae. You will need to maintain shock level or close to it until the pool clears. I don't know what you mean by "power vacuuming" but a pool can be vac'd blind. Might be a good idea if you can to first vacuum to waste, to get rid of some of the algae clinging to the pool suface. Shock after that. During this time try to brush the pool occassionally. Filter non-stop, and backwash when needed. Eventually the pool will clear, but you really are going to need some cya (again, assuming an outdoor pool).
    Poor Man's Pool
    Doughboy 18 ft round above ground
    7600 gal with center drain
    Pentair sand filter, 1 HP pump
    50 ppm borates
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    Pool Calc Ver 1.41 (Excel)

  3. Back To Top    #3
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD
    Welcome to TFP! With a little work we can turn this around in a week or two.

    You need to get your CYA up to at least 20 and prefferably 30 or you won't be able to hold a chlorine level and won't make much progress on the algae. Without CYA sunlight will burn off the chlorine very quickly during the day and the algae can get ahead of you.

    Basically, you need to bring the chlorine level up to the shock level based on your current CYA level, see the best guess chart link in my signature. Then you need to retest the FC level and bring it back up to shock level as frequently as possible, at least twice a day. When the FC level stays constant overnight you have killed the algae. It will still take the filter several days to clear the water at that point.

    While this is happening you should run the pump 24/7, brush the pool once a day, sweep up or vacuum out all the debris you can, and watch the filter pressure and backwash/clean the filter as needed or every several days in any case.

    GreenOut can cause it's own problems if not used correctly. It can consume huge quantities of chlorine making it even harder to hold a FC level. It can be handy in some cases, generally when your CYA level is very high, but doesn't sound appropriate for your situation.

    To start without any CYA, I would put seven pounds of CYA in a sock, either in the skimmer or hanging near the return. Add 5 gallons of 6% (or ultra) unscented bleach each evening for the first two days, and then start testing your FC level and adding enough bleach to bring it up to 15 at least twice a day after that.

    Once things are under control you can fine tune your calcium, CYA, and alkalinity levels.

    Good Luck
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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