High Pressure, low flow

[jbsmith22]

Hi all -
Since opening my pool this year (last week) the filter has been running funny. At startup it runs normally, low (5-8psi) pressure, good flow from all three return jets. Within about 20-30 minutes, however, the pressure has risen to around 25 psi and the flow to the returns has dropped to almost zero. Looking in the filter basket on the pump it's about 1/2 empty. As soon as I turn the pump off, water rushes back into it from the filter. If I then backwash it for a few minutes, and restart, the pattern will repeat -- it runs fine, though the pressure rises visibly, until around 20 minutes when the flow drops to near zero and the pressure stabilizes at around 25psi.

At this point I've run backwash/rinse (what IS the difference there?) enough that there's no DE left in the filter. Or at least none that can be removed by backwash. The check glass is clean on the backwash when I start and end it. The baskets on the skimmers and in the pump are clean.

I also have a valve that splits the lines from the skimmers and the drain at the bottom of the pool and checked both ways with the same result. It doesn't look like it's struggling to bring water in, anyway, it looks more like it's struggling to push it through the filter.

The outflow side of the filter has an inline chlorinator on it, and I've tried it with it turned to max as well as turned to off without a change.

Any ideas? Should I pop the cover off the filter and see if maybe something is dislodged? Seems weird though given that it works perfectly fine for at least a little while whenever I backwash and restart it.

Appreciate the help TFPers!

Jason

 

[Jimrahbe]

JB,

Sounds to me like the filter is doing its job. Algae plugs the filter and the pressure goes up, backwashing clears the filter and pressure goes down.

But, if this were my system, I would, without a doubt, open the filter and get rid of all the DE that has not come out via backwashing. After cleaning, add new DE, and see where you are.

What does your water look like and what are your test results?

Jim R.

 

[jbsmith22]

JB,

Sounds to me like the filter is doing its job. Algae plugs the filter and the pressure goes up, backwashing clears the filter and pressure goes down.

But, if this were my system, I would, without a doubt, open the filter and get rid of all the DE that has not come out via backwashing. After cleaning, add new DE, and see where you are.

What does your water look like and what are your test results?

Jim R.

Water was super-algae-ish on opening (next topic will be "do any winterizers really work, or am I just too stupid to apply them correctly") so don't doubt that the initial run would have plugged it up right nice with some algae.

Now, though, the water is a bit milky (since I can't really run the filter) but it's reasonably clear, there is some free chlorine in it and no visible algae. I have a Dolphin Nautilus cleaner (Amazon.com : Dolphin 99996323 Dolphin Nautilus Robotic Pool Cleaner with Swivel Cable, 60-Feet : Swimming Pool Robotic Cleaners : Patio, Lawn Garden) which I've run through about 10 times now and it comes out reasonably clean (or at least no algae) on the filters anymore.

So I don't THINK it's natural, particularly since backwashing runs clean right from the beginning. But it definitely could be that there's some clump of something or other in there that's plugging something up.