pressure back up within a few hours of backwashing the pool

[txpoolaustin]

I have a 7 year old pool with DE system, believe it is a FNS48 with the conical filter arrangement. Recently I noticed what appears to be DE coming back into the pool. Upon removing the top of the tank I found a crack in the manifold which I cleaned and fiberglassed. I also cleaned the filters. Upon reassembly and one final backwash, I noticed the pool pressure up to 30 PSI within two days. Last evening, I backwashed again. Came out this a.m. and same thing. Really doesn't appear to be any debris in the backwash but it does take the pressure back to about 21 PSI. Could this be a manifold problem. I am a do it your self guy but this is a mystery to me. Any help is greatly appreciated.

Thank you

[poolpro1]

How much DE are you adding after each backwash ? Have you added any chemicals to the pool that clear up cloudy water ? Your filter grids may need cleaning with a degreaser and acid or they may need to be replaced.

[txpoolaustin]

The pool is around 25K gallons and I add around 8-9 large scoops of DE, probably a pound each. I took the system apart and cleaned the filters, could not find any broken. The manifold was cracked and I fiberglassed it. The pressure held but the DE was right back in the pool again. I am going to order another manifold but am at a loss as to why the DE is coming back in the pool.

Any help/thoughts are appreciated.

[Guest]

8-9 lbs. sounds like a lot of DE to me. Make sure you go by the filter's instructions as per the SF of filter area. Obviously too much DE is a problem. As far as it getting back into the pool, the only way for that to happen is a crack in the manifild or a tear in the fabric on the grid.

If your water has been VERY cloudy, it is possible that the filter is just taking that much particulate matter out of the pool. If you have used a clarifier of any kind, this would add to the pressure buildup.

I would check the manual to make sure I'm not adding too much DE, check the manifold for any cracks, and clean the grid with a degreaser. If that didn't work, I would ditch the DE filter and go to a Sta-Rite System 3 Modular Media cartridge filter.

[rob the builder]

or you put the grids in wrong maby? 8-9 is fine i am going to guess just make sure all grids are in correct. and clean the filter more often and you will not have that problem with the top mani. cracking.

[ch132212]

So I have this very same issue. My pool is nasty right now, but it's been nasty before and I have never had this issue. Scenario below...

Pressure stayed pretty high this fall, then this winter the pump housing cracked bad. Replaced pump housing last week, replaced all of the filter grids (replaced manifold last summer), put it all back together, and without the DE I still have 15 pounds right away, and 30 pounds within 1.5 hours (I didn't realise that I was out of DE till I got all the work done).
This has been in the past week, by the way.

Now, with DE I get about 20 pounds almost immediately then 30 pounds within an hour or so.

I've never had this kind of pressure before, even after vacuuming nasty algae off the floor of the pool.

I'm lost and on the verge of giving in and paying someone to fix this hunk of junk. I'm almost ready to go with a sand or cartridge filter.

[Guest]

What pressure do you get on recirculate? Are you sure the pressure is from the filter?
Could be a return line blockage.

[Larry]

Pressure stayed pretty high this fall ...
... without the DE I still have 15 pounds right away

You could have a problem with the filter valve or on the return line.

Further to Pool User's advice, check the water flow or suction on filter and on filter bypass. If they are the same then the problem could well be a clogged return line.

Did the pump housing crack due to the weather?

Larry

[ch132212]

What pressure do you get on recirculate? Are you sure the pressure is from the filter?
Could be a return line blockage.

I only have two options... backflush and filter. ON backflush with a 30 foot hose I have about 8 pounds pressure. If I have a 10 foot hose it's only about 4 pounds, if even that much.

[ch132212]

Pressure stayed pretty high this fall ...
... without the DE I still have 15 pounds right away

You could have a problem with the filter valve or on the return line.

Further to Pool User's advice, check the water flow or suction on filter and on filter bypass. If they are the same then the problem could well be a clogged return line.

Did the pump housing crack due to the weather?

Larry

I just replaced the plunger valve for the filter/backflush (internals anyhow).

I'm assuming that the housing cracked due to age or continual high pressure. I let it run 24/7 in the winter for fear that my freeze-guard won't work when needed. Then again, I live in TX, I could probably just turn it on during the cold days.

[Larry]

Could you try to run the pump after removing the filter grids and see what kind of pressure registers.

It should be very low if the return lines are clear (probably similar to your backwash/ waste line pressure).

Larry

[ch132212]

Could you try to run the pump after removing the filter grids and see what kind of pressure registers.

It should be very low if the return lines are clear (probably similar to your backwash/ waste line pressure).

Larry

I actually considered doing this when the pressure gets back up to 30 pounds again.

I also am going to get a new pressure gauge. Just in case....

Thanks again!