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Thread: proper DE backflush prevents algae

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    Join Date
    Jul 2013
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    North Canton, OH
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    proper DE backflush prevents algae

    Mods - if this should be in the pumping station section, please move it as appropriate

    I wanted to share a recent experience.

    I got on the TFP methods about a month ago (thankfully) after getting hit with a big algae bloom that I could not resolve with the pool store advice. Things have been going well, and the pool looks great. I am still working on a few things like "Hey kids, if you pee in the pool, your eyes are going to sting - it is not the chlorine!" but things are going pretty well.

    Last weekend, I had a big pool party with a very heavy bather load for an entire day. The next morning, the FC had dropped to 1, and the CC was 0.5 or 1. I added liquid right away, and the FC recovered, and the CC went back down. So I thought I had caught it in time. And for the next few days, the pool continued to look good, and the chemistry looked fine. Then on the fourth day, I opened the pool to find it cloudy (barely see the shallow end bottom, can't see the deep end) and FC at zero - full blown algae bloom again - not as bad as the previous time (thanks to daily monitoring), but certainly not what I was hoping for.

    How the heck did that happen?? I thought everything was good!! I am following the TFP methods, so why did this happen?? Last night, I believe I figured out what happened. I noticed that the DE was running at a much higher pressure than I have ever seen, so I opened it up. It was really packed with DE and debris, and there were clearly areas that were not circulating. And those areas were black and nasty with algae (at least I assume that is what it was). And there were large areas of several grids that had a dark slimy film formed over the surface of the grid where the debris had been packed. So I cleaned it all out and got it all back together and running normally again. Then I came to TFP and started reading. And I read this thread http://www.troublefreepool.com/threa...for-DE-filters and the light bulb went on. I had been told to backflush for 2 minutes, rinse for 20 seconds and go back on line with a fresh full load of DE. After reading that, and getting the SLAM underway, the first time I needed to backflush I did it the way that thread explained. WOW! It was amazing how much more debris came out after the multiple flushes. My conclusion is that by not getting a good backflush and adding a full charge every time, I was allowing DE and debris to accumulate and eventually plug up the grids creating areas of little or no flow that were great for black nastiness to take hold. And once that nastiness got big enough, it overcame the FC in the pool, and voila - bloom city.

    The good news is that 16 hours into the SLAM after a mostly sleepless night of frequent testing and chlorine addition, I am already seeing dramatic improvement in the water clarity, and the FC consumption is starting to stabilize. I am guessing I will be out of the woods tonight and 100% good within 48 hours. Thank you TFP! And I thought I would call attention to one of the "Further Reading" threads that I think is quite valuable.
    30,000 gal IG 20x40 8ft deep end vinyl liner in NE Ohio DOB Sept 2012
    Hayward 4820 DE filter, Hayward SP2610x15 1.5HP single speed pump
    Hayward H400FDN natural gas heater, Frog min'l/Cl2 system (not in use)
    autocover, Dolphin DX4 cleaner, well water, TF100 test kit

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    Mod Squad kimkats's Avatar
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    Tallahassee, FL
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    Re: proper DE backflush prevents algae

    What an awesome post! WOW! Happy, fun, sadness, solution, happy, sharing! You hit it all!

    THANKS!

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Richard320's Avatar
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    San Dimas, CA (LA County)
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    Re: proper DE backflush prevents algae



    A second clogged filter image would be nice.
    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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    Join Date
    Jul 2013
    Location
    North Canton, OH
    Posts
    192

    Re: proper DE backflush prevents algae

    Richard - sorry bro - when I opened it up and found the mess, I was just thinking about getting it cleaned up - I apologize for dropping the ball and not grabbing some pics - if it happens again (I hope not) I will get pics
    30,000 gal IG 20x40 8ft deep end vinyl liner in NE Ohio DOB Sept 2012
    Hayward 4820 DE filter, Hayward SP2610x15 1.5HP single speed pump
    Hayward H400FDN natural gas heater, Frog min'l/Cl2 system (not in use)
    autocover, Dolphin DX4 cleaner, well water, TF100 test kit

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