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Thread: Filter Backwash - How often for DE?

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    Filter Backwash - How often for DE?

    Hi,

    Thanks to you guys i think I am going to save $1500 this year & handle my pool myself. I am starting to get the hang of things, I cleaned my DE filter about a week ago. My pool company opened the pool, cleaned the filter, added DE. A few days later it was still cloudy.

    I opened the filter, cleaned it, added more DE & off i went. A day or so later the water was clear.

    So my question is how often should i backwash the filter vs open the canister to manually rinse the grids?

    How much DE do I add when backwashing? How long do I backwash?

    Thanks so much for the help!

    Rich
    40k IG Gunite pool (47x21), Jandy iQ904-PS, Pentair 011018 VS Pump, Pentair 180009 FNS Plus Filter, Pentair 261152 Multiport
    Stenner Liquid Chlorine Dispenser - 30 gallon tank, Zodiac PB4-60 Polaris Booster Pump, Polaris 280 Pool cleaner
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    Mod Squad Jimrahbe's Avatar
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    Re: Filter Backwash - How often for DE?

    Rich,

    The TFP standard answer is backwash or clean when the clean pressure increases by 25%...

    Personally I never backwash, as I have variable speed pumps and run them at about 1,200 RPM most of the time. I open and clean them twice a year...

    This is not something you can do if your water is cloudy due to an algae outbreak..

    When I did backwash I added about 80% of the clean DE requirement. You backwash until the sight glass is clear, and I would do that twice..

    Thanks,

    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Caldera Spa.

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    Richard320's Avatar
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    Re: Filter Backwash - How often for DE?

    I use cellulose instead of DE and I backwash twice a year. I learned the hard way that once the pressure goes up 25% it's just a matter of days before it's up 50%. seems to be something with the cellulose, like it starts decomposing or something, since it is biodegradable. My backwash valve is integral in the base of the filter, so I backwash for a few seconds until the water out the end of the hose starts clearing. Then I open it up and remove the top manifold to get a little wiggle room and get in there with a jet spray nozzle to blast any sticky stuff off. Since it all drains out the bottom, it just runs out the backwash hose. Reassemble, flush again long enough to clean out the hose, and I'm done. Fifteen or twenty minutes is all.

    DE never rinses off completely, and cellulose even less so, in my experience, so opening it up is part of it for me.
    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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    Re: Filter Backwash - How often for DE?

    Quote Originally Posted by Richard320 View Post
    I use cellulose instead of DE and I backwash twice a year. I learned the hard way that once the pressure goes up 25% it's just a matter of days before it's up 50%. seems to be something with the cellulose, like it starts decomposing or something, since it is biodegradable. My backwash valve is integral in the base of the filter, so I backwash for a few seconds until the water out the end of the hose starts clearing. Then I open it up and remove the top manifold to get a little wiggle room and get in there with a jet spray nozzle to blast any sticky stuff off. Since it all drains out the bottom, it just runs out the backwash hose. Reassemble, flush again long enough to clean out the hose, and I'm done. Fifteen or twenty minutes is all.

    DE never rinses off completely, and cellulose even less so, in my experience, so opening it up is part of it for me.
    So yesterday I saw the pressure was at about 18, I backwashed for 30 seconds, turned it on & the pressure is sitting around 9. I added about 4 pounds of DE into the skimmer - is that pretty much all I need to do? The lower the PSI the less resistance within the pipes?
    40k IG Gunite pool (47x21), Jandy iQ904-PS, Pentair 011018 VS Pump, Pentair 180009 FNS Plus Filter, Pentair 261152 Multiport
    Stenner Liquid Chlorine Dispenser - 30 gallon tank, Zodiac PB4-60 Polaris Booster Pump, Polaris 280 Pool cleaner
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL Become a TFP Supporter!

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    Richard320's Avatar
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    Re: Filter Backwash - How often for DE?

    Quote Originally Posted by RichTJ99 View Post
    So yesterday I saw the pressure was at about 18, I backwashed for 30 seconds, turned it on & the pressure is sitting around 9. I added about 4 pounds of DE into the skimmer - is that pretty much all I need to do? The lower the PSI the less resistance within the pipes?
    That's it for normal backwashing. After you recharged it, that's your clean pressure. When it rises 25%, it's time again. For a plain backwash, we recommend 80% of the initial fill quantity, since it never washes out 100%. If you open it up and clean it all out, then you use the full amount.

    Check out DE Filter Cleaning Tutorial just for the worst-case picture. It's worth it.
    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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    Re: Filter Backwash - How often for DE?

    You guys are the best!
    40k IG Gunite pool (47x21), Jandy iQ904-PS, Pentair 011018 VS Pump, Pentair 180009 FNS Plus Filter, Pentair 261152 Multiport
    Stenner Liquid Chlorine Dispenser - 30 gallon tank, Zodiac PB4-60 Polaris Booster Pump, Polaris 280 Pool cleaner
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL Become a TFP Supporter!

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    Re: Filter Backwash - How often for DE?

    I notice that after doing a thorough cleaning of my 2 year-old pentair filter grids, including taking it apart and thoroughly spraying down and cleaning every bit of debris from fiberglass housing and parts) it needs a backwash again only after 3 weeks. The pool was used only a couple times and there is no unusual debris going into pool. 15k gallon pool. 60' filter. Put in 12 measured cans on DE. The pressure was great and the pool cleaned effortlessly at the beginning. Now I have to crank up pump to 3000 rpm to get barely anything to move. I will back wash again, but the frequency is getting closer day to day where I have to do it again.

    Don't know what the problem is.

    The filter grids looked great. Just under two years old anyway.

    Quote Originally Posted by RichTJ99 View Post
    You guys are the best!

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    Mod Squad Jimrahbe's Avatar
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    Re: Filter Backwash - How often for DE?

    my,

    The number one reason that filters quickly clog is because they are just doing their job. Most likely you have an algae outbreak and that is what is causing your need to backwash so often..

    Please post a complete set of numbers as follows...

    FC
    CC
    pH
    TA
    CH
    CYA

    Thanks,

    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Caldera Spa.

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    Re: Filter Backwash - How often for DE?

    The pool does get a green tinge on the walls and clouds pool after scrubbing. Last time I looked at grids they were as green as a shamrock.

    I will get those numbers. Many thanks, Jim.
    Charles.


    Quote Originally Posted by Jimrahbe View Post
    my,

    The number one reason that filters quickly clog is because they are just doing their job. Most likely you have an algae outbreak and that is what is causing your need to backwash so often..

    Please post a complete set of numbers as follows...

    FC
    CC
    pH
    TA
    CH
    CYA

    Thanks,

    Jim R.

  10. Back To Top    #10

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    Re: Filter Backwash - How often for DE?

    If you keep your chemistry in check, you may not ever need to backwash. I have never backwashed my filter. I just disassemble and clean it every 12-18 months. IMHO, if you're going to go through the hassle and mess of backwashing, you may as well go all the way and disassmeble for a thorough cleaning. Plus, by completely disassembling, you can precisely measure the DE instead of taking a guess at how much to add.
    7,000 Gallon In-ground Plaster Pool, Spa, & Waterfall
    Jandy Stealth Pump, Jandy DEV60 Filter, Jandy LXi400N Heater, 8 Gallon Liquidator, The Pool Cleaner
    Taylor K-2006C

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