Sand Filter Pressures

[waldreps]

I have an 18x32 inground pool with a PF-50 sand filter. I just opened my pool yesterday and started the pump and filter. It showed about 16 PSI on the filter to start with. Today, I checked it and it made its way to about 24 PSI so I decided to backwash. As soon as I started backwashing, the pressure dropped to 20 PSI but wouldn't go any lower. I let it backwash for a couple of minutes and the water was totally clear coming out of the hose. I rinsed to re-seat the sand and then went back to filtering. The gauge still shows 20 PSI. Why didn't it go down anymore than it did? It did this same thing last year and the only way I could remedy this was to replace the sand. I did that last year along with checking, cleaning and replacing the laterals, and it worked pretty normally for the rest of the year. Surely replacing the sand isn't going to be a yearly ritual for me. Is there some way to get the pressure to go down to normal levels? In years past, after backwashing, the PSI would be around 12 or 14. Is there something else that could be causing the pressure to stay so high? Any help would be appreciated.

Thanks,
Stacy

[aylad]

If this is the first time you've started the pump/filter, I would start by replacing the gauge. It's cheap, only takes a few minutes to do, and may be the solution to your problem. It takes very little moisture combined with cold air to render it useless!!

Annual replacement of sand is not a normal thing for a sand filter. If replacing the gauge doesn't help the problem, you need to start looking for something else. I'm not sure what, but there are other equipment folks around here that can offer some suggestions once they see this thread.

[waldreps]

Yeah, I don't think I should have to replace my sand every year. Last year when it did this, it was the first time I'd opened the pool in a couple of years and there was all kinds of goop in the pool. I can see how that would clog the sand filter. I drained the whole pool, cleaned and refilled and then replaced my sand. When I opened this year, the pool didn't look too bad except for a lot of fine dirt and silt that made its way through the mesh cover. As far as the gauge, it appears to work OK in that the dial moves freely like when I turn things off it pops right to zero and then goes back up when I turn things back on. I guess it could be reporting the incorrect pressure but I do notice reduced flow when the pressure goes up. If I take the eye on the return off, the pressure goes down by a couple of PSI. I just don't understand why backwashing doesn't cause things to go back down to at least where it was when I started it up this year. What kind of PSI reading should I be getting when I'm backwashing? Shouldn't it be quite a bit lower than the reading when I'm filtering? Thanks for any help anybody can give.

Thanks,
Stacy