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Thread: High filter pressure, low return pressure

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    High filter pressure, low return pressure

    Immediately after backwashing, I get decent suction on my vacuum and the returns which are pointing up are very vigorous except one return which occasional blows and doesn't blow as hard as the other two. After about 2 minutes of vaccuming which has the occasional leaf and some green gritty stuff on the bottom the pressure on my Sand filter rises to 30 and the returns are very weak. The one return doesn't blow at all. And I can easily break the suction on my vacuum in my skimmer. After I backwash everything works fine. I've sucked up far more stuff in a much dirtier pool in the past and didn't need to backwash every few minutes. I can't imagine that overwinter when it was unused until now it would be so bad. I had trouble getting my pool clean as we have had prolific rains and the pool almost over-flowed many times and had to be drained several times in the middle of a storm. I had a hard time getting my CYA stable and then all of the sudden I was throwing in 5 bags of shock and having it eaten up within minutes. It took soooo much shock to get it to shock level and hold. I don't know if that has an effect on the filter or not. But without vacuuming I'd still have to backwash every day. Overnight the pool filter pressure would climb to above 30. Oh and a few times the jets shot out very cloudy water. So..does that mean I need to replace the sand? Is this something that is safe for me to do? I mean I read a little on how to do it, but i'm a little nervous. Also I've seen a few say that its better to just switch to a DE filter. That sand is expensive and you end up saving money in the long run on DE. OH and I have no idea how old the sand is. We bought the home a few years ago. Thanks!
    Mom to two wonderful children, Navy wife and owned by a boxer.

    24,000 gallon, in-ground pool with Sand Filter. Size of filter is unknown. Vinyl liner.

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    Smykowski's Avatar
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    Re: High filter pressure, low return pressure

    How long ago did you open the pool? I closed a crystal clear pool last fall, but when I opened in the spring, I had to clean up a bunch of fine dirt and silt that made it through the cover. I was literally backwashing every 10-15 min for the first 3 hours of clean up.

    You could also try a deep cleaning of the sand. Search for "channeling." However, it sounds to me like you just have a dirtier pool this spring (I also saw the dirty cloud coming from the returns). Keep on trucking.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

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    Re: High filter pressure, low return pressure

    I opened it a while ago but didn't actually get around to vacuuming until now. I didn't seem nearly as dirty as the first two years we closed it with a ton of leaves and this time hardly any leaves but lots of green silt. Ok, I will keep trying. And I will check out channeling. Thanks!
    Mom to two wonderful children, Navy wife and owned by a boxer.

    24,000 gallon, in-ground pool with Sand Filter. Size of filter is unknown. Vinyl liner.

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    JasonLion's Avatar
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    Re: High filter pressure, low return pressure

    This all sounds normal for a pool that is dirtier than normal. Once you catch up on removing the spring debris from the pool things should go back to normal.

    Even if something is wrong, there is almost never any reason to replace the sand. It is catching debris just like it should.

    If this is bothering you, then you certainly don't want a DE filter. They will have the pressure go up like that and need backwashing in minutes rather than hours under the same conditions.

    Jets shooting out dirty water suggests that you may need to resettle the sand bed. But that shouldn't be related to you main issue.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: High filter pressure, low return pressure

    Then I definitely don't want a DE! I have a cousin who worked for a pool company. He got a call from an older woman about her pump making a funny noise. He got there and it was making a terrible noise and he asked how long it had been going on and she said 4 days. He looked at the gauge and immediately flipped the power off and the filter exploded. (this is all from his customer's statement). he was in a coma for 2 weeks and has severe brain damage as well his face was essentially caved in. Every bone in his face was shattered. Now im terrified of our pool pump. My pool guy assured me that i'd have to let it build incredibly high for a long time before something like this would happen...but i'm still scared. Ok...so just keep plugging away at it?

    Do those chemicals that are supposed to clean sand filters work?
    Mom to two wonderful children, Navy wife and owned by a boxer.

    24,000 gallon, in-ground pool with Sand Filter. Size of filter is unknown. Vinyl liner.

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    Mod Squad JohnT's Avatar
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    Re: High filter pressure, low return pressure

    How long are you backwashing? 3 or 4 minutes isn't excessive, and not backwashing long enough can make your filter act like you are describing.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: High filter pressure, low return pressure

    I backwash about 3 minutes. I really do it just until the glass is clear. Usually between 2-4 minutes. Then rinse for 30 sec.
    Mom to two wonderful children, Navy wife and owned by a boxer.

    24,000 gallon, in-ground pool with Sand Filter. Size of filter is unknown. Vinyl liner.

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    Re: High filter pressure, low return pressure

    So I opened my pool filter on top of the sand was this nasty gray silt residue and a ton of bugs. I haven't rinsed it out yet but want to make sure that that is normal. And that I don't need to replace anything. Thanks!
    Mom to two wonderful children, Navy wife and owned by a boxer.

    24,000 gallon, in-ground pool with Sand Filter. Size of filter is unknown. Vinyl liner.

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    Smykowski's Avatar
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    Re: High filter pressure, low return pressure

    Yes, that's normal. Dirty pool water hits the top of the sand, flows down to the laterals, then back to the pool. The top of the sand will be dirty if the filter is doing its job.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

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    Re: High filter pressure, low return pressure

    ok good...and gross. LOL Thanks as always!
    Mom to two wonderful children, Navy wife and owned by a boxer.

    24,000 gallon, in-ground pool with Sand Filter. Size of filter is unknown. Vinyl liner.

  11. Back To Top    #11

    Re: High filter pressure, low return pressure

    I cleaned it out and its start up pressure is now 2-3 psi lower at start up than its ever been since we bought this house. The return that was low pressure is working perfect. Its suction is fantastic. I'm so glad I did this and didn't buy 200 lbs of sand and labor through that. Thanks sooooooo much!!!!
    Mom to two wonderful children, Navy wife and owned by a boxer.

    24,000 gallon, in-ground pool with Sand Filter. Size of filter is unknown. Vinyl liner.

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