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Thread: Unusual Sand Filter Problems

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    Unusual Sand Filter Problems

    This all started last year when I changed the sand in my Hayward S-210T sand filter and replaced it with zeolite. Since that time, the pressure does not increase on the sand filter to indicate the need to backwash. Instead, I know I need to backwash when the level starts dropping in the pump filter basket. I know that air in the top of the pump basket often indicates a leak on the suction side of the system, but several things lead me away from this conclusion:
    1. I have isolated the main drain line and skimmer line separately and the amount of air does not change.
    2. The level in my pool is not dropping other than the normal small amount expected for evaporation.
    3. We recently had a power outage that lasted at least 4 hours and the pump never lost prime and started right up when power was restored.

    The pressure gage is working fine because I replaced it just last year and the pressure I see is what I would expect for a clean filter for any given pump speed.

    Also, I donít know when this next issue started, but I bought a robotic cleaner this year and noticed that it picks up about a half cup of sand (maybe less) if I run it every day. How much sand was in there to begin with and what percent it is picking up each time I don't know.

    What is going on here? I know that the sand entering in the pool probably indicates a broken lateral in the sand filter even though I was extra careful when I changed the sand and followed the proper procedure (add water first, cover the standpipe, etc.). It is one of those folding lateral assemblies so I could kind of understand if one of them had been damaged when I folded them up to remove the whole thing from the tank.

    The sand filter is a dozen years old, so my question is should I replace the lateral assembly (about $75) or do I need to replace the whole thing (several hundred dollars)? I replaced the spider gasket about 3 or 4 years ago and really hadn't had any problem at all with the filter until I replaced the old sand last year. If it was just the sand blowing into the pool, I would just get the lateral assembly, but I donít understand these other things I am experiencing.
    21k IG vinyl, Pentair Intelliflo, Hayward S-210T Sand Filter, Hayward H150 Heater

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    Mod Squad woodyp's Avatar
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    Re: Unusual Sand Filter Problems

    Welcome to the forum. The water level dropping in your pump filter basket shouldn't be related to any issues you may be having with your sand filter. You are correct in assuming that the "water dropping" and air there being due to a suction side leak of some kind. Lube the gasket on that lid basket cover? A broken lateral is most likely the cause of sand entering your pool. Does your new gauge return to zero with the pump off?
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
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    Re: Unusual Sand Filter Problems

    I thought of lubing the gasket, but hadnít done it yet because it takes a great deal of force to remove the pump basket lid after the pump has been running and because of it holding prime so well. The only other common leak point would be on the pump side of the 2 valves coming from the main drain and skimmer. I had a leak there with a previous set of valves due to cross threading a connection, but at that time I couldnít even get the pump to prime and start. I suppose there could be a leak at a connection point like at the suction opening itself, but there is nothing evident. I donít know if there would be some easy way to test that. The new gage does return to 0 when the pump is off.

    That still wouldnít explain why a dropping water level would indicate the need to backwash. It is very noticeable too, not just a few more bubbles in the pump lid. It probably drops to at least a half inch below the top of the basket. I do not know if it would get worse than that because I donít want to take a chance on running the pump dry. After the backwash the level is back up with just a few bubbles in the lid.

    I just canít seem to wrap my head around the mechanics of what is happening. Let me go ahead and throw out my crazy theory so someone can shoot it down if there is no way it could be correct. I am in agreement that there is some kind of lateral damage causing the sand in the pool. What if there is channeling going on inside the sand filter? When the sand is clean, the water can either go through the channels or through the clean sand. When the filter needs to be backwashed, the water can only go through the channels. Since there is little or no back pressure the pump canít keep up with the water flow at the speed I am running it. The gage reads about the pressure I would expect because it is basically reading the discharge pressure of the pump. Does this make any sense at all or have I gone off the deep end?
    21k IG vinyl, Pentair Intelliflo, Hayward S-210T Sand Filter, Hayward H150 Heater

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    Mod Squad woodyp's Avatar
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    Re: Unusual Sand Filter Problems

    I guarantee if that sand filter has never had a deep cleaning....you're in for a surprise as to how actually dirty that thing is! I went 5 years without doing mine-------never again. There is an article in Pool School describing how to do this. It also sounds to me like you could also have some possible blockage in a line if the water level in the basket is dropping as you describe as well.
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
    Pool Rover Jr., Pool Blaster Max, Diver Dave TF100 Test Kit/Speed Stir
    Margaritaville Frozen Concoction Maker, Liqour Chiller, & Drink Mixer & Party Tub----Collect 'um all!

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    Mod Squad JohnT's Avatar
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    Re: Unusual Sand Filter Problems

    A clogged filter could potentially cause issues in the basket, but I'd think you'd see a pressure rise before that happened.

    Might be interesting to see what happens to the gauge and in the basket when you rotate your return eyeballs 90 degrees to restrict flow.

    Maybe a dumb question, but have you verified that your inlet and outlet are plumbed correctly from the pump to the filter and from the filter to returns?
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    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Unusual Sand Filter Problems

    Woodyp

    I’ve never done a “deep cleaning” of the sand filter before so I will have to check out Pool School to see what that is all about. The last time I just drained all the water, removed all the sand, removed the standpipe and laterals (probably how they got damaged), and hosed it out real good.

    Where do think the blockage might be? I doubt that it would be on the suction side, so is there some way a blockage on the discharge side could cause these things?

    JohnT

    Yeah. The lack of a pressure rise is puzzling to me as well. I am not sure what you are saying with the return eyeballs. Are you saying to move the center part around so that the jet is partially restricted? If I want to restrict flow, it might be easiest to just remove one and replace it with a cap. I could probably get away with that if I ran my pump at a slower speed. No dumb question, but the pool has been there a dozen years. The only thing I plumbed in the last few years was the pump and it is kind of hard to mess that up.
    21k IG vinyl, Pentair Intelliflo, Hayward S-210T Sand Filter, Hayward H150 Heater

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    Mod Squad woodyp's Avatar
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    Re: Unusual Sand Filter Problems

    Where do think the blockage might be? I doubt that it would be on the suction side, so is there some way a blockage on the discharge side could cause these things?

    I'd say check the skimmer line first. But it's just a guess.
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
    Pool Rover Jr., Pool Blaster Max, Diver Dave TF100 Test Kit/Speed Stir
    Margaritaville Frozen Concoction Maker, Liqour Chiller, & Drink Mixer & Party Tub----Collect 'um all!

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