Sand Filter at 37-40 PSI (help?)

Hi all!

The pressure in my filtration unit is reading really high (37-40 PSI). I haven't done anything to different to the pool over the last couple of weeks. Typically the pressure is around 15-20 PSI.


So my questions are:
1) what causes the fluctuation?
2) what can I do to reduce pressure if I catch is creeping up?
3) what troubleshooting steps can I take to figure out the actual problem?

Other factors that might help:
-I recently cut down the pump's hours (from 12 hours to about 5 hours per day)
-The water level fluctuates, but has never been so low that water doesn't flow through the skimmer basket

Have you back-washed the filter? With sand filters if backwashing doesn't immediately lower the pressure, you know something else is wrong.

Most pumps can't even produce 40 PSI. Even if it could, it would be very close to dead head so my guess would be a bad guage. Either that or you have all your return valves shut off.

Does the guage go to zero when the pump shuts off?

Also, what size/model pump do you have?

Thanks for the replies...

I have noticed that:
1) my dog scratches the nearby lawn and the grass is thrown to the pool. It settles at the bottom and much of it has made it into the drain at the bottom.

2) when I turn the Jandy valve to the drain (and cut off the skimmer basket), the pump goes crazy loud and no water seems to be flowing from the drain side into the pump filter basket

3) I have backwashed twice. The pressure on the gauge is pegged at the high end. I turned off the pump for a couple of days and the gauge dropped to zero. But when I turned it back on, the pressure rose to the top of the gauge again.

4) the drain at the bottom still has a little suction, because recent storms in Phoenix have thrown leaves in my pool and the leaves seem to be drawn to the drain and move back to it when I move them away.


I'm thinking that I have a clogged drain line and something wrong in the pool filter (perhaps it's got all the grass my dog has put into the pool...)

Is there a flow chart for pump related issues?

What happens if you cut off the low drain and just open the skimmer?

I must admit it sounds like SOMEHOW the return circuit is clogged, too. Do you get a strong pressure at the return?

Could the sand in your filter be all gummed up?

Is your multivalve working correctly?

That noise from the pump when you were on the main drain was probably cavitation due to a blockage in the suction side. As Carl suggested, what happens when you're on the skimmer alone? It also isn't clear how long it took the pressure to rise from the normal 15-20 to pegged. Over a period of days or what? That could be a clue. Mark is right in that most pool pumps won't hit that pressure even when totally blocked, but could easily reach 30 or a little higher. The gauge is probably not totally shot since it still reads zero when off. For $10 you can get a decent one. And no, we never put together a troubleshooting flow chart. If any grass clippings got past the pump basket and into the sand filter, backwashing should clear it. You are using chlorine for sanitation aren't you? Reason I ask is Baquagoo can plug up a filter. We'll figure this out eventually.
Hope this helps.
Al

BTW: Just a reminder for all when posting. The forum is popping up parsing errors more frequently now so use the 'ctrl C' to copy to the clipboard before posting your response or previewing it. Just in case you lose it. Saves retyping.

Thanks for all of the great responses and pointers. Here's what is still going on...

The gauge is now completely pegged. I had the pump off during a cold spell here, and while it was off, the gauge went to zero. But within hours of being back on, the gauge was pegged (over 60PSI).

When I cut over to the main pool drain, no water pulls through into the pump. You can see there is no water in the filter cover and the pump starts making loud noise. When I cut back over to skimmer basket, it corrects.

I have backwashed, rinsed, and reset the multiport valve to filter.


My stabilizer is at 120 and minerals are very high. I am going to drain the pool and then see about taking apart the drain. After thinking about the components and the complete system, I think it's a clogged drain (or pipe) and possibly old/clogged/calcified sand in the filter. I think that starting here will get it going.

It is impossible for the pressure to reach 60 PSI so it sounds more like a bad gauge. For some gauges, the maximum PSI is actually 30 PSI. Are you sure that it is hitting 60 PSI? If so, replace the gauge because it is not reading correctly.

Quote:

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When I cut over to the main pool drain, no water pulls through into the pump. You can see there is no water in the filter cover and the pump starts making loud noise. When I cut back over to skimmer basket, it corrects.

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That means there is a blockage in the main drain line. Are you sure there isn't a plugged somewhere.