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Thread: Filter Issues

  1. Back To Top    #1

    Filter Issues

    Howdy to all...summer's almost here! That means it's time to try to resolve an issue from last year.

    Some history:

    Since I've had this pool, the clean filter pressure has been 29 psi. The weird thing is that the pressure never increases, it only goes down...mostly because of the pump strainer basket as there is a forest of pine trees right next to the pool and all those needles fit through the holes in the skimmer baskets & main and get caught up in the pump basket (or impeller ) But it also goes down when the filter gets dirty...it goes back up after backwashing.

    I replaced the sand in my filter early last year because it didn't seem to be filtering very well and we had bought the property with no history other than we knew the pool had obviously been installed for at least ten years.

    After cleaning the laterals - the slots were completely jammed with grains of sand in them - I replaced the sand. I began to get little piles of sand building up in the pool under the returns. At first I thought maybe it was just washing out the new sand that was fine enough to fit through the slots and would dissipate. It did improve some by the end of the season, but not completely and the water still wasn't as clear as it used to be (but had good chemistry) I was attributing that to the excess sand getting pumped back in.

    But after pondering it for a bit, I'm wondering if the sand is making it past the lateral slots because the pressure is so high that it is forcing sand through them...perhaps it didn't do that with the old sand because it had been thouroughly "rinsed" of all the finer particles and those grains that were jamming the slots effectively reduced the size of the slots. Long story less long... after replacing the sand, the clean pressure stayed at 29 psi.

    Another tidbit...I have a SWG cell that is installed downstream of the filter. Somehow, a small amount of pine needles and other debris (dog hair, small bits of various organic clutter) manage to get past the filter and lodge in the plates of the cell. It's not a huge amount, but enough to warrant cleaning it about every six weeks. I took the top of the filter off and the sand looked normal - no channelling or bio-mat.

    I was VERY careful when putting the new sand in the filter - put water in first, SLOWLY poured the first couple of bags in and CAREFULLY bedded the laterals down, so I would be very surprised if I broke something.

    I have a 1 1/2 hp A.O. Smith pump motor, but cant find any data tag or number or anything on the pump itself.

    I thought about reducing the pump size, but with all of the organic load the pool gets, and the fact that it's a very weird shape, I need all the circulation I can get - I keep it running 24/7 and still have a hard time with debris on the bottom. If the pump is in fact too big for the filter, does anyone have any thoughts on adding a second filter in parallel with the first? Maybe a different media - to increase filter capacity while reducing the pressure and keeping the flow up.

    So to clarify, my questions are:

    Why am I getting sand through the returns?
    Why is the pressure so high?
    Why doesn't the pressure increase when it needs a backwash?
    Is adding a second filter in parallel a good idea?

    I'm just getting ready to open the pool - we had over a foot of snow and fifteen degrees a couple weeks ago and even with the cold spring we've had, I've got a swamp again...sigh. I figure if I'm going to change the filter set up, I might as well do it now.

    Sorry for the and TIA and for all the past help just with the plethora of great information...the PS guys don't like me anymore because I quit buying all their stuff when you all taught me the right way to take care of a pool!

    Mike
    25k gallon, plaster IG pool in the shape of a "J"
    ABS thin tube solar system
    Hayward SWG
    Polaris ATV suction side pool cleaner
    Jacuzzi Lazer 250L sand filter
    1-1/2HP AO Smith pool/spa pump
    In beautiful Ft. Collins, Colorado

  2. Back To Top    #2
    Mod Squad Bama Rambler's Avatar
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    Re: Filter Issues

    Given the preponderance of evidence, I'd say that you have a cracked stand pipe, broken lateral, bad stand pipe seal, etc. and it's allowing sand and debris through the filter. You may actually have more than one issue.

    I wouldn't worry about another filter until you've solved the problem with your current one. Pool filters are designed to operate at 50 psi so it's highly unlikely that the pump could force sand through the laterals unless something is wrong.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  3. Back To Top    #3

    Re: Filter Issues

    I'm guessing there's no practical way to check for any of those issues without taking the filter back apart, including removing the sand to visually inspect the parts?
    25k gallon, plaster IG pool in the shape of a "J"
    ABS thin tube solar system
    Hayward SWG
    Polaris ATV suction side pool cleaner
    Jacuzzi Lazer 250L sand filter
    1-1/2HP AO Smith pool/spa pump
    In beautiful Ft. Collins, Colorado

  4. Back To Top    #4
    Mod Squad Bama Rambler's Avatar
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    Re: Filter Issues

    That is correct.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  5. Back To Top    #5

    Re: Filter Issues

    Gee...thanks a lot! <--- Notice the sarcastic font!
    25k gallon, plaster IG pool in the shape of a "J"
    ABS thin tube solar system
    Hayward SWG
    Polaris ATV suction side pool cleaner
    Jacuzzi Lazer 250L sand filter
    1-1/2HP AO Smith pool/spa pump
    In beautiful Ft. Collins, Colorado

  6. Back To Top    #6

    Re: Filter Issues

    I'm pretty confident I found the problem!

    I took my filter apart and the diverter was sitting at a strange angle just inside the neck. The standpipe inside the filter is way (1 1/4") too short. This leaves enough play in the slip joints between the diverter/basket assembly and the standpipe to allow anything sitting on top of the sand (sand included) that gets picked up the the eddies and current to get forced right back out the standpipe - which would be the path of least resistance - instead of through the sand and laterals.

    I'm not sure why it was too short or how it got that way. The manual suggests that the installer has to cut it to fit depending on what kind of valve is used so maybe they didn't push the pipe all the way into the slip joints because the fittings were new and tight, but over time loosened enough to let them slip fully into the socket - It's very easy to bottom the pipe in any of the sockets now.

    This also explains why I've never been happy with the filtering of my pool.

    I can't put it back together until the pool supply store opens on Tuesday so I can get more sand...I'm estimating 50-75 lbs has washed out of the filter

    After I get the pool opened and un-green, I will post an update on the filter performance.

    Thanks for the help and input Dave!


    Mike
    25k gallon, plaster IG pool in the shape of a "J"
    ABS thin tube solar system
    Hayward SWG
    Polaris ATV suction side pool cleaner
    Jacuzzi Lazer 250L sand filter
    1-1/2HP AO Smith pool/spa pump
    In beautiful Ft. Collins, Colorado

  7. Back To Top    #7
    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    Location
    SouthWest Alabama
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    22,347

    Re: Filter Issues

    Glad you found it, but bummer that you had to take the filter apart to do it.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

  8. Back To Top    #8

    Re: Filter Issues

    As promised, I am updating my filter performance after repairing the standpipe and adding 100 lbs. of sand!

    The filter works great and my water is always sparkiling clear!

    For whatever reason, the clean pressure is still high (according to most other reports) at 24 psi. I backwash at 30 and everything seems to be working as it should.

    It's amazing when you have the right tools to do the job and equally amazing when they are working as designed!

    Mike
    25k gallon, plaster IG pool in the shape of a "J"
    ABS thin tube solar system
    Hayward SWG
    Polaris ATV suction side pool cleaner
    Jacuzzi Lazer 250L sand filter
    1-1/2HP AO Smith pool/spa pump
    In beautiful Ft. Collins, Colorado

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