DE filter pressure rising fast after cleanout

[anonapersona]

I am here trying to help a friend (and to interest him in coming to the fourm).

The pressure on the DE filter is starting out normal and rising to 30 psi within an hour. When the filter is shut off, it goes back to normal then takes an hour to rise again. I know nothing about DE filters but it sounds to me like this is a mechanical issue.

Jeff said he cleaned the DE filter. Then he added 3 scoops (pounds?) of DE. Something wasn't right (Jeff is not here now so I'm trying to recall) so he called the pool store and they said that wasn't right he needed to add 7 scoops. So he added 4 more scoops.

I will be able to add more info in the morning regarding filter and pool specifics. I have no test data. Pool is not completely clear and has a slight green tint, just a bit. Jeff said he shocked it twice (bag of cal-hypo) and uses tabs for chlorine. The heater was on for the pool party and these issues were going on before all the kids and dogs were in the pool. I'll try to test the water in the AM using whatever they have for testing and will post that data as I get it but I am sure that what is immediate is a mechanical issue.

Is there something that went back together wrong that let DE into the pool so that the filter is not filtering right now - how would the pressure rise? Or is there something in the lines somewhere? I did notice rubber duckies in the skimmer, maybe one got sucked into the lines but how would that create this rising pressure?

In over my head, can anyone help?

 

[JasonLion]

There are couple of things that can happen which have that symptom. First, if the water is dirty, say in the middle of an algae outbreak, that is completely normal. DE filters very well and can get lots of debris out of the water quickly. When you turn the filter off the DE often falls off the grids and some of the dirt stays on the bottom, so the pressure doesn't go right back up instantly. It could just be that the filter is really dirty and needs to be throughly cleaned out. You also see something very much like this if you put in too much DE initially. DE alone can raise the filter pressure if there is too much, but it takes it a while to settle down against the grids and really block all of the flow. Again it falls off when the pump goes off, and the process repeats.

 

[zea3]

It is probably dirty again. Tell him not to bump or backwash the filter and not run the pump for a couple of hours, drain the filter and open it up. You should see a thick coat of DE on the grids and a couple of inches of DE in the bottom of the filter. I have opened mine when the water was a little cloudy and seen bright green on the DE. It catches debris that well!

Pull everything out, hose it clean, hose out the bottom of the filter and put it all back together. How much DE it takes depends on the size of the filter. I have a 36 sq ft filter and it takes 4 lbs of DE as per the label on the filter body. Putting in too much DE will also cause significant pressure rise.

 

[anonapersona]

Yes. I finally realized that he had mentioned putting "Cleaner" into the pool, and said he used it again after he cleaned out the filter. So he had two doses of flocculant in the pool. After I posted last night I read in Pool School about DE filters, since I've never had one, and that helped. This morning I explained what the "cleaner" was and came to the conclusion to backwash the filter. I doubt that he has done that, since they have plans this AM.

I will forward your instructions to him.

 

[frustratedpoolmom]

He may need to soak the filter grids/fingers - use the instructions in Pool School. I saw huge improvement on one of my filters after following the process. Used the detergent method first and was going to do the acid bath if it didn't work but it did the trick the first go-round.

 

[anonapersona]

One question, is using a "cleaner" that is a flocculant redundant with a DE filter, since they can do such a good job?

 

[JasonLion]

I don't recommend using floc at all. However, it is not redundant with DE. Clearing a seriously dirty pool takes a whole day of monitoring and cleaning the DE filter, while flock can clear the pool overnight plus some vacuuming. But floc has complications and fails to work correctly often enough that I don't recommend it.