DE filter pressure builds 15 pounds in couple of hours

[jdmnyc]

I have 72SF DE filter which had a bad grid that I just replaced. Went thru 50 lbs of DE previously and now realize that most or all of that went into pool. With filter clean the pressure initially read 15 pounds. I started to vacuum from bottom (still can't see) and it quickly slowed down water flow within 5 minutes. Pressure read around 35 so I backwashed and stopped vacuuming. Recharged with DE but within 2 hours the pressure was back over 30. Pool is very cloudy with algae and I figured that I was picking up additional DE as water has that milky cloudiness. Went thru several more cycles of pressure raising 15 pounds or more within couple of hours. Quit adding DE after each backwash as I figured it was picking some up from pool. When I backwashed the water too dirty and one time before backwashing I opened filter and it didn't seem to be too gummed up. I suspect that there is something else going on that is leading to rapid buildup of pressure other than DE filter getting clogged. Any ideas or suggestions?

[TSH Tech]

Too much yucky stuff in the pool gumming up the grids very rapidly and building up pressure rapidly. Oils and sap will gum up filter grids making water flow painfully slow and filter pressures high. They will look clean, but to the human eye, the grids are blocked! The best way to break down sap and oils is with a spray filter cleaner.

As a pool tech, if I were hired to clear up your pool I would go to your filter, remove your filter grids, reseal the filter and run a Flocculant treatment(entire bottle) in the pool. I'd run the pump for 2 hours and set the timer peg to shutdown at that time. Then let it work overnight till the next morning/noon until all the yuck settles to the bottom and the water is clear again.
I'd then take a portable pump and vacuum your pool with a discharge hose into the sewer system that leads to a utility treatment plant. Never into a septic tank! Or if there was an open field or waste canal if a sewer line could not be available. This would remove all the yuck out of the pool leaving only clear water behind.
In the meantime, while the Floc is working, I'd disassemble the grids, clean the grids with a spray filter cleaner and rinse to have it ready for re-assembly after the portable vacuum was completed.

If you do not have access to a portable pump, there is the long tedious method of using what you have. Backwash the filter, and then just start vacuuming. Don't recharge the filter again with DE. You already have DE at the bottom of the pool, right? There you go.
You're going to have to go through a few processes of Vacuum, backwash, vacuum backwash until most of the DE and yuck is out of the pool. When it looks like you have most of the rough yuck out, give the filter a quick cleaning and put a few scoops of DE in the filter. Don't fill it to capacity with DE, just enough to 'scrub' the water clean because you're going to have to backwash it yet AGAIN to wash out the remaining yuck. When the pool water looks like it's almost clearing up, give the filter a good cleaning with spray filter cleaner and recharge with DE and let the pump run. By then you should be able to see in improvement in water clarity.

final note, if you do completely disassemble your filter grids from the manifold, be sure to inspect each and ever filter grid for holes and tears. Check for gaps between the grid material fabric and where the grid slides into place on the manifold. Gaps can cause problems. Common places for holes are all along the seams where they are sewn together and every now and then a hole will develop in the middle of the grid. If the hole is small/tiny, you can buy a little time with clear silicone if you don't want to buy a grid or two just yet.
One small hole can ruin your pool filtering ability and will definitely blow DE through back into the pool. Yes, a small hole makes that much of a difference!