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Thread: algae bloom

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    algae bloom

    I have had sucess keeping my above gound pool clear for a few years. This year we lost a return line during a freeze some months ago. The pump emptied everything but about 6 inches of water out the return line before we realized there was a problem. There was some algae on the pool bottom but it was not solid over the bottom and the water was clear. This past weekend we filled the pool. We are on a water well with hard water. I had a gallon of algicide handy and I put it in. We started tablets and the pump and filter seemed to be working ok. When the pool was full it was a cloudy blue. Over the next couple of days the water never cleared. We backwashed daily and added a couple of ounces of sparkling blue each day. Wednesday the pool went from a cloudy blue to green. Last night I shocked it with 4-5 pounds of shock. Today it continued to be green. Filter is/has been running 24/7. I shocked again this evening with 6 pounds. And I backwashed the filter again.

    Numbers: right after the pool was filled.

    Total Alkanity 200
    PH 7.2
    Chlorine 0

    We tried to lower the total alkalinity by adding muratic acid (about a gallon over 2 days)

    But all that did was lower the ph to where we had to add soda ash and now we are at:

    ph 7.8
    total alkanity 250
    chlorine 0

    I also started another floater with tablets so there are two floaters with 4 or so tablets in them.

    so...........i got a green pool, annbody got any ideas?

    pool is 24 feet diameter, 4 feet deep, 13k gallons

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
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    SW Indiana
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    Re: algae bloom

    Welcome to TFP.

    You'll never get anywhere with floaters and tablets. Too slow in releasing chlorine.

    Read these articles. The first three cover algae cleanup and shocking, and the fourth will help get your TA down. Don't even worry about the TA until you get the water clear.

    Defeating Algae

    Turning Your Green Swamp Back into a Sparkling Oasis

    Shocking Your Pool

    Lowering Total Alkalinity
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: algae bloom

    JohnT referenced some great material for you. Some advice I can add specifically for your situation (which is already stated in the linked material) would be to not try and raise your pH with soda ash when your TA is already too high. You'll need to use acid to lower the TA and aerate to bring the pH back up (which won't raise the TA). As for the algae, you'll have to keep adding chlorine to keep the FC level where you want it. With a lot of algae it will go down quickly, but you have to stay on top of it.

    Some extra information that would be helpful: What kind of test kit are you using? What is your CYA level?

  4. Back To Top    #4

    Re: algae bloom

    Thanks guys, guess all I really needed was more chlorine and patience, it is back to cloudy blue again this morning, but substantially clearer, you can actually start to be able to see the bottom a little now. Test kit is a Leslies deluxe dpd kit, so I don't have a test for cya, but I am pretty sure its pretty low since I just filled it a few days ago from a water well.

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    Join Date
    Jun 2007
    Location
    NC
    Posts
    255

    Re: algae bloom

    Quote Originally Posted by bayeye
    Thanks guys, guess all I really needed was more chlorine and patience, it is back to cloudy blue again this morning, but substantially clearer, you can actually start to be able to see the bottom a little now. Test kit is a Leslies deluxe dpd kit, so I don't have a test for cya, but I am pretty sure its pretty low since I just filled it a few days ago from a water well.
    If the water level was down to ~6" before you started filling it you are probably aright about the CYA... Adding CYA via a floater will not add it fast enough to prevent the chlorine that you are adding from being burned off in the sun. You can buy 100% or 96% CYA (conditioner, stabilizer, etc.) at Wal-Mart. Until you have CYA in the water you are going to continue to have to use lots of bleach.

    Make sure to brush the pool. Brushing keeps whatever algae there is exposed to the chlorinated water, where the green dies and turns a blue-grey (or is it "gray"?). Your steps are...
    1. Keep up with the bleach. Floaters won't do it...
    2. Add CYA to help protect the chlorine that you do have in the water.
    3. Brush, brush, backwash when the pressure gets high.
    4. Have POP (pool owners patience)..

    You have to know your CYA level to know your shock level and chlorine levels, so I'm recommending a TF-100 kit from http://tftestkits.net/splash-page.html.
    It has everything you need.

    Terry in NC
    Triad Region of NC
    18x37 Vinyl IG (24,000 gal.), BBB & GoldLine AquaLogic PS4 SWG, Hayward 1 HP Superpump / Hayward Sand Filter / Polaris 280 cleaner / 6 deck jets / Sheer Descent Waterfall (in coping) / Brick Red Concrete Coping / Stamped Concrete Deck
    Lots of oak trees, maple trees, *and* leaves!

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