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Thread: Sand filter and DE

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    meatloaf's Avatar
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    Sand filter and DE

    In the newsletter it mentions something about adding DE to a sand filter. "Filter aids such as DE powder or cellulose fiber, however, can help improve sand's filtering ability. ", How would this be accomplished?
    Thanks
    My pool is a 10,500 gallon (420 Sq Ft ) kidney shape. A hand made sheer decent waterfeature. STA-RITE HRPB30, Sand filter 30" 98 GPM,
    1 HP Maxi-Glas 2 pump, BBB Method, Taylor K-2005 test kit, 50 Watt 12V low-voltage pond light illuminates the pool at night for a nice soft glow.
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    JasonLion's Avatar
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    Small amounts of DE can be added to a sand filter after each backwash to improve the filtering. The first time around you need to figure out how much DE to use. Start by noting the PSI reading on the filter. Then mix 1/4 cup of DE with water in a bucket and pour that slowly into the skimmer. Give the system about a minute to stabilize. Note the pressure on the filter and continue adding DE until the pressure has gone up one PSI. This will typically take around 1-2 cups of DE. Subsequent times you can simply use the same amount of DE you figured out the first time around all at once.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    replacement of sand

    Jason,

    Will this technique require more frequent replacement of the sand? I understand sand should last about ten years.

    In you opinion how effective is adding the DE? Does it make a noticeable difference? Can you still see a difference between a DE pool versus a sand pool?

    Thanks,
    Light grey plaster, stone coping, 38K gallon Roman shaped pool with a shallow end beach, table and bar stools, deep end bench and waterfall (Intelliflo 4X160). Taylor K-2006, Pentair 320 chlorinator, Intelliflow VF, Quad DE 100. 4 ColorLogics, 3 skimmers, 14 wall returns, 13 floor returns, TurboTwister slide, autofill and miles of pvc.

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    just weighing in here:
    but earth is a much better filter
    keeps the pool cleaner and can clear up a pool much faster

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    JasonLion's Avatar
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    DE does not really affect the lifetime of the sand. There are two main schools of thought on how long sand lasts. One says replace the sand every five years. The other says that sand last essentially forever as long as it doesn't get too badly clumped (which depends on chemistry rather than time). It is possible to see the difference between old sand and new sand in a microscope and some people are able to see a difference in the water as well.

    I can reliably tell if DE is being used with a sand filter (with old sand) or not by looking at the pool but some of my friends can't. Others report a similar range of experiences, some notice some don't. My take is that sand+DE is not as good as a true DE filter but is better than sand alone. Keep in mind that some people can't tell plain sand apart from a DE filter, while others spot it instantly. How important all this is to you is really a matter of personal taste/perception.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    but earth is a much better filter
    keeps the pool cleaner and can clear up a pool much faster.
    Well, yes and no. In a real mess, like an algae bloom, DE will clog almost instantly requiring backwashing far more often than sand. So, like many things in life, it depends.....
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    i agree but i can always make time for backwashing
    a little note:
    when i take off my loop-loc cover my water looks like pea soup (not many trees in yard total sun)
    i backwash every hour on the hour
    all day long (like 10 - 12 times)
    and of course i shock at the same time but in a day i can get it clear
    i could never do that with a sand filter

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    What's the micron difference between sand and D.E?
    16' by 32' cornelius AG vinyl liner, 6' deep end, 14500 gal.
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    Sand is around 40 to 60 microns, cartridge around 20 microns, and DE is around 5 microns. ZeoLite in a sand filter claims 5 microns, some pool cleaners claim 2 microns. If you run the filter at very low flow rates you can go smaller than that.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Quote Originally Posted by JasonLion
    Sand is around 40 to 60 microns, cartridge around 20 microns, and DE is around 5 microns. ZeoLite in a sand filter claims 5 microns, some pool cleaners claim 2 microns. If you run the filter at very low flow rates you can go smaller than that.
    So with that said, would it be feasible to say, adding DE to a sand filter could bring the micron filtration down to about 20?
    The reason I'm asking is at night with the light on in the pool you can see tiny partials floating around in the water but not during the day. I wish I had a picture of it to post, but the pool is still frozen . I would like to get ride of it but if I have to spend a bunch of money for a new filter I think I could live with it. What is Zeolite? Is that like a DE?
    16' by 32' cornelius AG vinyl liner, 6' deep end, 14500 gal.
    Hayward 250 Lb sand filter
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    2-2' by 20' sun grabber solar heater.
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    JasonLion's Avatar
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    Quote Originally Posted by 98xc600
    adding DE to a sand filter could bring the micron filtration down to about 20?
    Maybe, no one really knows. Empirically the water looks rather like water from a cartridge filter but the way it works is probably different. I believe that it catches some fraction of the particles between 5 and 40 microns, but who knows.

    Zeolite is a naturally occurring mineral that has many small pores, kind of like a sieve. There are a couple of brands available, for example ZeoSand. In an ideal world it will get everything down to 5 microns, but in practice there can be complications. Zeolite tends to crush and sometimes that crushed zeolite gets through the filter and into the pool. So occasionally it can end up actually adding dust to the pool instead of removing it. Also, it is possible for the pores to get clogged, and then it behaves more like new sand and less like DE. Many people love it. At the same time it probably gets more complaints than all of the other kinds of filter media put together.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    meatloaf's Avatar
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    My pool is a 10,500 gallon (420 Sq Ft ) kidney shape. A hand made sheer decent waterfeature. STA-RITE HRPB30, Sand filter 30" 98 GPM,
    1 HP Maxi-Glas 2 pump, BBB Method, Taylor K-2005 test kit, 50 Watt 12V low-voltage pond light illuminates the pool at night for a nice soft glow.
    250 gallon stand-alone hot tub. Got it FREE!

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    There are other parameters in addition to the filter medium that have a large impact on filter effectiveness. Last year, I switched from an older DE filter rated as just adequate for my sized pool to an oversized sand filter. I noticed no difference in water clarity, not even at night with the pool light on. I tried adding DE to the sand filter after backwashing; that made no noticeable difference to water clarity in my case, yet shortened the interval for backwashing.

    The lesson I draw from this: The size of the filter may have as much or more impact on water clarity than the filter medium.

    Coty
    22,000 gal, IG vinyl, 3/4 hp pump, 300lb sand filter (switched from DE), converted from baquacil (thanks to Ben), BBB since 2004

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    The lesson I draw from this: The size of the filter may have as much or more impact on water clarity than the filter medium.
    Amen, brother! I am convinced that everything else is peripheral. It is virtually impossible (but occassionally impractical) to get a filter that is TOO big.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    on that theme

    As an owner/builder I have been agonizing over the filter decision for some time trying to minimize maintenance but provide a crystal clear pool. I will be at about 45K gallons so I have decided that I will use a large Pentair DE filter. My flow rates will be low probably about 40gpm over 19 hours. My hope is that I can go a whole season without needing to backwash. I have read on the forum that backwashing DE filters is somewhat questionable due to never really knowing how much DE was washed out and needs to be replaced. Instead of backwashing I hope I can make it through each season then just remove and clean the grids. Then I can recharge with fresh DE in the proper amount.

    I am tempted by the large TR140 sand filters but 600 pounds of sand and 3 ft wide!

    Pentair has the FNS series , the 2000 series and the 4000 series DE filters. If anyone has experience with these different lines, please provide a recommendation or other useful information that I could use to make a decision.

    Thanks.
    Light grey plaster, stone coping, 38K gallon Roman shaped pool with a shallow end beach, table and bar stools, deep end bench and waterfall (Intelliflo 4X160). Taylor K-2006, Pentair 320 chlorinator, Intelliflow VF, Quad DE 100. 4 ColorLogics, 3 skimmers, 14 wall returns, 13 floor returns, TurboTwister slide, autofill and miles of pvc.

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    With Filters, bigger is better. The rule of thumb is when your clean pressure gauge reading increase 7 - 10 psi, it's time to backwash.

    The Pentair 2000 vs 4000 series are the same filter but with either a stainless steel tank (2000 NS series) or a fiberglass tank (4000 series - hence the F in FNS).

    The frequency of backwashing depends on the pool usage and the amount of debris entering the pool.

    I have a cartridge filter that I clean about every other month. I have a 19K pool, not a typical screened enclosure around the pool as in most South Florida pools, so I get my plenty of tree debris in the pool. My suction side "Great White" cleaners also has an inline leaf trap (the best thing since sliced bread and salt systems), that traps a whole lot of debris before getting the pump basket and cartridge filter clogged up. I simply clean that out when it gets visibly overloaded with "stuff".

    Unfortunately, the little floaties in the water, especially at night with the pool light on, will occur with any of the three filters, although the DE may be capable of removing more than a cartridge or sand filter. You will still see that at night.
    Sean Assam - Sean@teamhorner.com
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    I have a Pentair Clean and Clear 150 with an uprated 1.5 HP wihisperflo (same as a full rated 1hp) on a 7k gal pool. Talk about oversized! the pump and filter are sized at commercial and not residential ratings (one of the things my pool builder did right!). I clean it monthly but it could probably go a year before I have an 8 psi pressure increase! I use my pool a lot at night and the water stays pretty clear, especially since I added the borates to the water. (For some reason borates seem to increse water clarity. I suspect it's because they stop nascent algae blooms.) I have tried experimenting with a chitosan based clarifier for a while (they are the best kind to use with carts) but I did not notice any difference except for a 'greasy' residue on the cart and inside the filter that had to be cleaned off!

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    meatloaf's Avatar
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    Re: Sand filter and DE

    I've run my sand filter both ways, with and without DE and yes I can definitely tell the difference. Without DE the filter will go about 2 - 3 weeks before I need to backwash. With DE it will go about 5 days. Also at night with the light on there are far less tiny particles floating in the water. I use about 4 cups of DE in my filter.
    My pool is a 10,500 gallon (420 Sq Ft ) kidney shape. A hand made sheer decent waterfeature. STA-RITE HRPB30, Sand filter 30" 98 GPM,
    1 HP Maxi-Glas 2 pump, BBB Method, Taylor K-2005 test kit, 50 Watt 12V low-voltage pond light illuminates the pool at night for a nice soft glow.
    250 gallon stand-alone hot tub. Got it FREE!

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