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Thread: First time backwashing - DE grid filter - does this sound right?

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    Join Date
    Apr 2014
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    First time backwashing - DE grid filter - does this sound right?

    Hey folks - first time pool owner and moved into the house in March. Read pool school diligently on here and went through pool school with a local pool company. The grids were in good shape in March and manifold is brand new. The pool guy did the first cleaning (to teach me how to do it) and filled with DE. The base pressure when he did it was just a shade over 22 lbs. I do have pop-up cleaning heads.

    Monsoon season is winding down and my pressure was somewhere between 4 and 5 lbs over the baseline. I needed to learn how to do this anyway and things are about to get busy so I thought I would knock it out.

    After backwashing and replacing the DE, then letting the pump run for about a 1/2 hour, the pressure is just a shade under 26 lbs. Everything appeared to go smoothly (I followed the use and care for DE filters thread advice) and I only added the 80% amount of DE, not the full 100% of 7.5 lbs.

    The result is my pressure has only dropped one, maybe two lbs. I have watched the pressure closely for the past few months and it has always been stable with a very slow climb. I did not watch the pressure that closely immediately after I bought the house, mainly because I had no idea what I was doing.

    Is this normal? Should my pressure have dropped back closer to the original baseline set by the pool guy? I have kept the pool clean and in balance thanks to new pool owner neurosis and have never had any issues with algae. The pool was drained and re-filled shortly after my pool school visit.

    One other thing I noticed - almost immediately after restarting the pump after backwashing, the pressure gauge was hovering right around the baseline. It is the first time I remember seeing it there since the pool guy was here. Is it possible the pool guy had simply set the baseline too quickly, prior to the system having a chance to pressurize?
    19K PebbleTec in-ground with spa, Hayward Super II pump, DE 60 series filter, T-15 SWG
    Water feature, Hayward Northstar pump

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    Mod Squad zea3's Avatar
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    Re: First time backwashing - DE grid filter - does this sound right?

    When you backwash a DE filter, not all of the old DE is removed, and it tends to cake up over time. If the flow from the returns is strong then everything should be ok. If the flow from the returns does not feel as strong as it should then you may want to open up the filter and hose off the grids. Also try backwashing for a longer period of time to give it a chance to flush everything out.
    TFP Moderator
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    Apr 2014
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    Re: First time backwashing - DE grid filter - does this sound right?

    Thanks for the reply. Return water flow seems fine. Being a backwashing virgin, I was stunned by the power of the water. The hose was flying all over the place! I don't know how many time I backwashed and then ran normal flow...at least four. It was tough to tell when the backwash was clean because it was throwing so much nasty **** from the ground around. I may have to invest in a better backwash hose that I can control.

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    Mod Squad jblizzle's Avatar
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    Re: First time backwashing - DE grid filter - does this sound right?

    You should be able to get a feel for the cleanliness of the backwash by looking at the sight glass. Well, maybe that assumes you have a multi-port valve.

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    Jason, TFP Moderator
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