DE shoots into pool after recharge


Gold Supporter
Mar 20, 2018
Austin, TX
After backflushing my DE filter and recharging, DE shoots into the pool slowly over the next several weeks.

I had the filter professionally disassembled/inspected -- no problems found. I also replaced the multiport valve. The problem continues.

My backyard is sloped and the equipment sits about 4-5 feet below water level, causing increased water pressure on the multiport that perhaps affects its seals. Water seems to seep slowly through the multiport even when it is closed (multiport is new, and spider gasket looks fine). I don't know if an imperfect multiport seal would cause DE to leak into the pool, or if perhaps the DE filter itself has invisible defects. The DE filter is unknown age, probably 10+ years (?). My pool guy is stumped.

I was thinking about scrapping the DE filter and buying a new cartridge filter, until I realized how much small debris (pollen, seeds, etc) falls into the pool in spring & fall. I must backflush 2-4 times each spring and fall, and I don't want to disassemble a cartridge filter that often. Backflushing the DE is way faster/easier than filter disassembly.

Any thoughts about either (a) solving the DE leak, or (b) using a cartridge filter in a high-pollen area (two large trees nearly overhanging pool, which I will not cut)?


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
What is the part number of the MPV you installed?

Post pics of the DE filter and MPV. Your symptoms can be caused by the wrong MPV installed with the water in and out ports reversed.


Gold Supporter
Mar 20, 2018
Austin, TX
Allen, thanks for the info.
While searching for more details, I found a slightly different pdf on the Praher website:

This pdf suggests that the multiport itself should be hooked up differently for a sand vs DE filter, which is very puzzling (shouldn't in be in and out be out, regardless of what stuff is inside?).

Based on the orientation of my multiport, my setup is correct based on your pdf, and correct for "sand" in my pdf, but incorrect for "DE" in my pdf. This is very confusing.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

I "assume" that over the years you have added DE to your filter without any issues, and then one day, it started to leak back into the pool. Is that true?

What, if anything, did you do just before it started leaking? Did you replace the MVP before or after the leak?

Logic says that the most likely problem is a bad grid. How old are the grids... ?

Seems to me that the problem has to be the grids, a cracked manifold, or maybe a missing O-Ring.

If this were my pool, I'd probably replace the grids, no matter what the "professionals" said about them.


Jim R.


Gold Supporter
Mar 20, 2018
Austin, TX
Jim, thanks for your thoughts.

The problem arose semi-spontaneously. Backflushes worked fine, nothing really changed, and one day the recharge caused DE in pool. I had a professional disassemble+clean+inspect after that first incident. He didn't see any defects, and it did not fix the problem. Then I had a professional replace the multiport. It did not fix the problem.

I have owned the house for 3 years. Best guess is filter is 7-14 years old. I'm fine replacing the grids, and maybe I should replace teh whole filter, so I get a brand new manifold, o rings, everything).
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