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Thread: Adding a DE filter after the sand filter?

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    JesseWV's Avatar
    Join Date
    Apr 2011
    North Central WV

    Adding a DE filter after the sand filter?

    For awhile I've been dissatisfied with the small particles that still make it through my sand filter. I've followed advice to add DE to the sand only to be disappointed to see the DE itself returning to the pool because the sand isn't even catching all of the DE!

    Today I was cleaning out the attic area of an out building and it seems the previous home owners left a Hayward EC40 Extended Cycle DE filter! It was partly disassembled with a ziplock back full of nuts, bolts, and washers down inside. The "flex tubes" were all stained green from what I assume was algae.

    I downloaded the PDF manual for the model and looked at the diagram and quickly realized it was not put back together correctly. They had bolted the two tube sheets directly together with the diaphragm underneath instead of in between! I spent some time removing each flex tube and hosing them off until they were nice and white again. One of the tubes was cracked off about 2 inches down. I plugged this tube with silicone sealant and let it dry. I put them all back through the tube sheet and properly put the whole thing back together.

    I plumbed the DE filter in after the sand filter but before the SWG. I turned the sand filter to "Recirculate," turned on the pump and waited for air to clear the lines. I then added 4 lbs of DE to the skimmer per the filter instructions. I waited and watched the return for a good 30 seconds after the pump basket went clear, still no white cloud entering the pool! I turned off the pump and switched the sand filter back to "Filter" and turned the pump back on.

    I now have a 2-stage filtration system that gives me coarse filtration through sand and fine filtration through the DE!

    I did notice the clean pressure on the sand filter went up from 15 psi to 19 psi, which could be due to the "Flow Controller" that goes into the DE filter.

    So is this as effective as I think it is? Are there any downsides to this set up?
    16k gal, 28'x3.5', Vinyl A/G, 1hp Pentair Dynamo 2-speed Pump, Hayward S160T Sand Filter, Intermatic HB800RCL Digital Timer, Intex 8110 SWG, TF-100 Test Kit, SpeedStir Author: Jesse's Graphical Pool Testing Log

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    Casey's Avatar
    Join Date
    Apr 2007
    SW PA

    Re: Adding a DE filter after the sand filter?

    It sure does sound effective MacGuyver! Someone else will have to get into the technical side of efficiency. I do love my DE filter though!
    I'd bet you my bikini you'll never get TFP water from a pool store!

    24' Sharkline Venture De Filter

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    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Adding a DE filter after the sand filter?

    The down side is increased head loss and lower flow rate ... maybe that does not matter though. Any reason not to just remove the sand filter? Sounds like there is something wrong with it anyway if debris passing. Hundreds of sand filter owners use DE and do not see it enter pool.

    I don't think we would ever recommend someone going out and buying 2 filters. But since you happen to have them, it is an interesting experiment I suppose.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
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