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Thread: Is it Possible to Over Over-Size a Filter - DE in This Case

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    Is it Possible to Over Over-Size a Filter - DE in This Case

    Examples Please. Thanks, gg=alice
    1981, 25K, IG, Blue Plaster 1996, somewhat oval, widens a bit at shallow end, 1.5" pipes, 2" at Pad, 1 separate main drain, 1 skimmer, 4 returns + dedicated cleaner return, 10 ft deep end with very fast decline from shallow, Pentair Quad 80 DE, Pentair Intelliflo VF, 3/4 HP Booster Pump (equipment pad about 8 ft below top of pool), Challanger 3/4 Trash/Emergency Pump 120v, Polaris 280 (pressure), iRobot Verro cleaner (robotic), Aquabot Turbo (robotic), Jacuzzi Tracker 4X (vacuum) Pool Blaster (Buster), Two (2) PoolSkims, Solar Breeze (solar powered top skimmer) (beta to ver. 2, release date 2010), ColorSplash LED replacement bulb. Aries 550 gal separate spa, 2002 (our 3rd and BEST spa) , BBB-Bromine

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    Re: Is it Possible to Over Over-Size a Filter - DE in This Case

    Alice, it would be VERY hard to oversize a residential DE filter A larger filter results in better filtration (as opposed to one that is at the max gpm for the pump).

    Have you been offered a great deal on a monster sized filter? If you'd tell the folks like mas and Jason the pump and filter specs, they could help reassure you
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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    Re: Is it Possible to Over Over-Size a Filter - DE in This Case

    Quote Originally Posted by waste
    Alice, it would be VERY hard to oversize a residential DE filter A larger filter results in better filtration (as opposed to one that is at the max gpm for the pump).

    Have you been offered a great deal on a monster sized filter? If you'd tell the folks like mas and Jason the pump and filter specs, they could help reassure you
    Thanks much, much, much. Boy I wish someone would make that kind of offer on the one I want. I've been needing to go pick up the Pentair Quad DE 80 for several weeks now, but things come up. Just doing some more rereading today about head, pipes, flow, etc... and doing a rough estimate of my head loss and gain, I was just wondering if could maybe even move up to the Quad 100. Of course that would mean digging down a little deeper to get the vertical clearance for it.

    My pump is a 1.5, SF 1.5, so essentially a little more than a 2 HP. My limiting factors are the pipe sizes. BTW... with the tiny 36 DE filter in this pool for 28 years it's a wonder the grids last as long as they do.

    I'm going to be starting a thread with pictures of my pumping station for advice on the Flex pipe I need to run from the pad to the new filter which will be about 5 ft away from the pad and down the hill a bit, with multi valve about 36" lower than the push/pull on old filter.

    I have two suction side, 1.5" each, main drain and skimmer, that connect to a 3-way valve, leaving valve via 2" to pump. From pump is a 2" going to filter valve.

    One (1) 1.5" leaves the filter. There is a reducer on the valve, reducing from 2" to 1.5" where the one line goes to four pool returns. The 1" or so hose for 3/4 hp booster comes off the return line at one point, goes to pump, and leaves pump through same type of hose to 3-way valve and then to 1.5" dedicated return. I use a Polaris 280 on that.

    Before I added the two (2) PoolSkims and reducer eyeballs to get more water to the PoolSkims the clean starting pressure on filter was usually around 13 (after good clean/soak of grids and fresh DE). After a couple of backwashes (2-3 times a week) and adding less media to compensate for retained media in filter, the starting pressure is 15. It's been this way for the 23 years we've lived here.

    Putting the two reducer eyeballs on returns for PoolSkims' success now makes the starting pressure at filter 19 psi. Now that I have the PoolSkims I can't imagine how I ever managed without them. I have to have one of the cleaners running about 12 hours a day to keep the large, small, tiny, and teenicy debris cleared from pool. Our "silt" is so tiny I'm thinking it probably works with the cellulose for filtering. It sure does raise the psi quickly though. This year we acquired the three puppies that are, now, in and out of the pool all day, dragging in more sand/silt than the other dogs we've had who didn't swim as much. In addition this has been the worst year ever for flying silt but it is much better now that we've gotten about 20" of rain since early Oct. I just switched to cellulose end of summer and I'm pretty sure it is filtering finer, also, than DE.

    Would the larger filter reduce some of the head at pumping station? I can't increase pipe sizes. I am happy with the pressure and suction but only doG know how much energy I'm wasting with big pump, undersized filter, and small pipes.

    When I run the suction cleaner, Tracker 4X, I can usually start with main drain partially open but as filter psi increases (lots of fine stuff going to filter) I have to close off most of the main drain. It is the only cleaner that will get the really, really, tiny stuff to the filter fast enough for me without getting stirred up, as it does with the Polaris. BUT it does a lousy job on the leaves as compared to the pressure side Polaris-280.

    I'm not going to go any smaller than the Quad 80 but I was wondering if there would be any disadvantages to getting the 100 other than up front cost. I guess that's a question.

    Thanks, I'm working on marking up the pictures for when I start the topic on pipes and fittings for new filter.

    gg=alice
    1981, 25K, IG, Blue Plaster 1996, somewhat oval, widens a bit at shallow end, 1.5" pipes, 2" at Pad, 1 separate main drain, 1 skimmer, 4 returns + dedicated cleaner return, 10 ft deep end with very fast decline from shallow, Pentair Quad 80 DE, Pentair Intelliflo VF, 3/4 HP Booster Pump (equipment pad about 8 ft below top of pool), Challanger 3/4 Trash/Emergency Pump 120v, Polaris 280 (pressure), iRobot Verro cleaner (robotic), Aquabot Turbo (robotic), Jacuzzi Tracker 4X (vacuum) Pool Blaster (Buster), Two (2) PoolSkims, Solar Breeze (solar powered top skimmer) (beta to ver. 2, release date 2010), ColorSplash LED replacement bulb. Aries 550 gal separate spa, 2002 (our 3rd and BEST spa) , BBB-Bromine

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    mas985's Avatar
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    Re: Is it Possible to Over Over-Size a Filter - DE in This Case

    More than likely your pump is producing no more than 85 GPM so technically, a 60 sq-ft filter would be sufficient to handle that flow rate and still have 25% margin. Unless you plan on ever using a bigger pump, there is probably little to gain going larger except for longer time period between backwashes but would require more DE to recharge. Certainly a 36 sq-ft filter is way too small for your pool and pump but I see no need to go above 80 and really only a 60 is needed.

    Also, most of the head loss in a DE filter is due to the backwash valve so going to a larger filter doesn't really help that.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner

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    Re: Is it Possible to Over Over-Size a Filter - DE in This Case

    Quote Originally Posted by mas985
    there is probably little to gain going larger except for longer time period between backwashes but would require more DE to recharge.

    That is the first and virtually the only reason I'm upsizing the filter as the old one is in great shape (late summer I drug it out from under deck, soaked the grids and replaced a few). For 23 years the old one has needed a weekly backwash, year round, (the main reason I switched to cellulose is my BW water goes down hill to protected woodlands and adds to our already heavy silt problems). Each year we've been here, 23 yrs, with water coming down our gravel drive from the rest of the hill, just a few feet higher than us (20 ft max), has increased as new houses are being built AND even more silt comes with it. One side of our property is a natural run off for a major part of the hill. The silt was worse this summer than ever before in addition to the three new puppies that spend a lot of time getting in and out of the pool. So now, my tiny filter is (actually I am) overwhelmed with the amounts of silt, requiring usually 3 backwashes a week; occasionally only 2. With that much silt going in the old filter will also need to be taken apart for good cleaning more often too. 60 sq ft might be just fine for usual circumstances but our circumstances are EXTREME. That's why I want at least an 80. And a 100 if the rest of the system will handle that.

    The amount of filter media will even out as I won't be backwashing nearly as often. That's the least of my concerns. BTW... my neighbor with the "new" IG pool (3-4 yr old) has a Pentair FNS 60 that doesn't require backwashing very often BUT they don't have much of any silt issues and they have an automatic cover that stays closed most of the time. In addition her dog doesn't use the pool nearly as much as mine do (she comes over here a lot to swim with my dogs), dragging in even more silt than the wind blows in. Also, although their house is only about 100 yards from ours, we get much more wind. We are separated by our common, my "front 40" (a little less than an acre) woods, that protect them from a lot of the prairie winds that come up our valley.


    Certainly a 36 sq-ft filter is way too small for your pool and pump but I see no need to go above 80 and really only a 60 is needed.

    60 for normal circumstances. Major question is will the 100 sq ft be okay to use? That would mean even less backwashing. BTW... the Quad can be cleaned well by taking top off and rinsing with hose instead of the 100's and 100's of gallons it takes to backwash the very fine silt out.

    Also, most of the head loss in a DE filter is due to the backwash valve so going to a larger filter doesn't really help that.

    Thanks. I remember reading about that. I will be replacing the ancient push/pull with a multivalve. The old one probably has added loss as I can't get it all the way closed to lock it and have to use a rubber mallet to move it down far enough to keep water from escaping out the waste. I, also, can't pull it up, for backwashing, enough to lock it either. It is pretty stiff so it really doesn't need locking in either position. I replaced o-rings, in past couple of years (and other parts over the years), but the interior "tube" is gritty. It is so bad that, starting last year I can't even get the plunger out to lube or replace o-rings.

    There is another section of pipe that is coming out on pressure side where I used to have a commercial vessel for Nature 2 and an obsolete Nature 2 express, not used in 3 years, but left on because I have planned to replace that whole section anyway. (With the Express you drill a hole into the return pipe and then clamp it on. If you fully winterize you take it off but I can't do that without repairing the pipe as I normally keep the pool open in winter.) That redo will reduce some head on the pressure side of filter.

    I'll be posting pictures, hopefully, tonight when I start a topic asking for advice on pipes and fittings I need for the upsize/move.

    So..... would a 100 be out of the question?

    BTW.... People usually don't really believe me about our challenging environment until they experience it. I may exaggerate about some things but it's kind of hard to do when explaining our environment.

    Thanks much. gg=alice

    1981, 25K, IG, Blue Plaster 1996, somewhat oval, widens a bit at shallow end, 1.5" pipes, 2" at Pad, 1 separate main drain, 1 skimmer, 4 returns + dedicated cleaner return, 10 ft deep end with very fast decline from shallow, Pentair Quad 80 DE, Pentair Intelliflo VF, 3/4 HP Booster Pump (equipment pad about 8 ft below top of pool), Challanger 3/4 Trash/Emergency Pump 120v, Polaris 280 (pressure), iRobot Verro cleaner (robotic), Aquabot Turbo (robotic), Jacuzzi Tracker 4X (vacuum) Pool Blaster (Buster), Two (2) PoolSkims, Solar Breeze (solar powered top skimmer) (beta to ver. 2, release date 2010), ColorSplash LED replacement bulb. Aries 550 gal separate spa, 2002 (our 3rd and BEST spa) , BBB-Bromine

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    mas985's Avatar
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    Re: Is it Possible to Over Over-Size a Filter - DE in This Case

    If your primary object is to maximize the time between backwashes then by all means go with the 100. I was just saying that proper sizing is a 60 so anything at 60 or above is fine.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner

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    Re: Is it Possible to Over Over-Size a Filter - DE in This Case

    Thanks bunches. I appreciate the assistance. Now to start digging the "hole" to see if I want to deal with the added vertical clearance needed for the 100. I can't stand up straight to dig the hole in 90% rock. My rock breaker rod is also too tall to use under there. Sure wish I could direct the dogs where to dig. They can make craters in short time.

    gg=alice
    1981, 25K, IG, Blue Plaster 1996, somewhat oval, widens a bit at shallow end, 1.5" pipes, 2" at Pad, 1 separate main drain, 1 skimmer, 4 returns + dedicated cleaner return, 10 ft deep end with very fast decline from shallow, Pentair Quad 80 DE, Pentair Intelliflo VF, 3/4 HP Booster Pump (equipment pad about 8 ft below top of pool), Challanger 3/4 Trash/Emergency Pump 120v, Polaris 280 (pressure), iRobot Verro cleaner (robotic), Aquabot Turbo (robotic), Jacuzzi Tracker 4X (vacuum) Pool Blaster (Buster), Two (2) PoolSkims, Solar Breeze (solar powered top skimmer) (beta to ver. 2, release date 2010), ColorSplash LED replacement bulb. Aries 550 gal separate spa, 2002 (our 3rd and BEST spa) , BBB-Bromine

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