Sand Filter Issues

[djonesax]

I recently installed a used 26" baqapure / 200lb sand filter on small 5000 gallon pool. I have the pump set at 1750 RPM filtering 12 hours a day, and chlorine dispenser on the line running back to the pool. I really need some help figuring out some problems I am having. I have posted this on another forum but no one seemed to want to help.

Here are the issues I am having...

1. My water has this haze that I think must be sand particles floating in the water and then they settle out to the bottom because I get what looks like sand on the bottom of the pool.
2. When I change the port position on the multi-port valve the water gushes out of the backwash port. When I get it back to filter it still comes out of the back wash port just slower. I can usually get it to stop by tapping the multi-port handle with a rubber mallet. I have a hose connected to the backwash port and just have it going back into the pool so the drip doesn't create a swamp. The water that is coming out of it looks clean unless I have it on backwash.
3. I am reading between 0-5 PSI on the pressure gauge but most of the time it is 0 PSI
4. The suction on the pump seems to drop after a while and the only way for me to restore it is to change the position of the multi-valve port and then move it back to filter and the suction is strong again.
5. When I hook up the vacuum, it works well for a little while and then the suction drops. I can restore it by changing the port position like above.

I really want some help on this. I have cartridge filter system that I can use in place of the sand filter system but don’t want to swap it out unless I absolutely have to. I spent a lot of time and money wiring up this system which is 220 and the other is 110.

Thanks,

David

[CarlD]

Whew! A lot going on! 12 hours a day for a 5K pool? That's about 4 times longer than you need--I'd run that size filter on MY pool and it's 20k. Are you running at low speed? is that what you meant?

Now the problem is almost certainly in your multiport valve. I'm not the MPV expert but you symptoms sound like
a) A perforated or broken wall between channels in the MPV
b) A damaged and/or out-of-goove spider gasket.
c) A damaged valve mechanism.

That's what I'd check first.

[djonesax]

The water had this constant haze so I kept filtering longer and longer to try to get rid of it. I was doing 24hrs a day for a couple weeks. Wife wasn't happy about the power bill. I'll drop it down.

If I took apart the MPV would I be able to see if there were a damaged or perforated wall and is the MPV easy to take a part? The handle came off once by accident because the pin slipped out. I was able to get it back in but took some effort. I don't mind taking the entire thing apart as long as its one of those things that I can get back together by reversing the steps. I would just hate to have it apart and then need some special tool to rebuild it.

Yes the pump is on low speed at 1750 rpm. High is 3500 rpm.

David

[Poconos]

Did a Google on that filter and it looks like you can take the valve apart easily and far enough to check the internals. It looks similar to the Haywards. Put the handle in a middle position, between settings. That relieves pressure on the spider gasket so the halves won't spring apart when you next remove the 6 bolts that hold the top and main body together. The top should lift right off. Shouldn't need to take it apart further to see if the spider gasket or the valve pieces themselves are damaged.
As for the problem of the flow decreasing, I can't explain that yet. The leaking out the waste line is as Carl suggests. If that valve has a recirculate or bypass position I'd try running in that mode to see if the flow drops. This mode bypasses the filter. If the flow symptoms still occur then it's something else in the system causing the problem. Quite possibly the pump. Let us know what you find and we'll take it further.
Al

Edit: Also, what happens to the pressure reading when you switch to high speed and what's the pump rating?

[CarlD]

Al is far more knowledgeable about the multi-port valves and the workings of the pumps than I am so I'll let him take it.

I've only had my MPV apart once and never pulled apart the pump...It ain't broke so I'm not fixing it!.