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Thread: DE coming through the returns only at start up.

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    ffournier's Avatar
    Join Date
    Apr 2015
    Houston Texas

    DE coming through the returns only at start up.

    Hi ladies and gentlemen. I applogize, for this may be a rather long post. I'll keep it as short as possible but hope you'll read it and give me your input. About a week ago I figured it was time to clean my Pentair 60 DE filter. It had been a long time, and also the first time I personally had done it. In the past I had it done. I did my research and found it to be pretty straight forward. I several of the panel necks that fit into the manifold to be cracked so I ordered a whole new set from Amazon. They showed up two days later, all assembled with a new manifold and vent tube. I closely inspected everything and found no problems. I cleaned out the tank, checked and siliclone lubed the O rings, installed the filter, started the pump, added the DE and all was well. No DE coming through the returns as I added the DE or afterwards. After a few hours I shut off the pump to replace the pump basket with a new one. But about 10 seconds after restarting the pump, clouds of DE came pouring into the pool through the returns. This lasted about 5 seconds and stopped. I shut off the pump, waited a few minutes and restarted it. Same thing happened. About 10 seconds of clean return followed by about 5 seconds of DE clouds then clean return again. Today I removed the filter again and inspected everything VERY closely but found no problems, except for maybe one thing, the screen on the new vent tube. As you can see in the pictures below, the "screen" on my old vent tube is not a screen, it's a very porous cylinder. Although the screen mesh on the new vent tube is very fine, it doesn't prevent even dry DE from passing through, much less when the DE is in solution. Please see the short videos below. With no air in the tank, is this vent tube completely submerged? I'm guessing that when the pump is running the screen may be exposed, but gets submerged when the pump is shut off, allowing DE to pass through the screen? Does anyone know if this is true? It's the only thing I can come up with given everything else is new Pentair parts, not knockoff aftermarket, and properly assembled. Any input would be greatly appreciated.

    25K gal saltwater gunite and Pebble Tech plus built in spa. Features-Weeping rock wall, and fountains. All Pentair equipment. Main pump- Intelliflo 4/160. Feature pump- Intelliflo 2hp single speed. Aux cleaner pump-Pentair 1hp. DE filter, Pentair heater, Glacier GCP210 pool chiller.

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: DE coming through the returns only at start up.

    DE coming through when the pump starts is normally caused by very small tears in the grid fabric. The tears let DE through for a moment before clogging up with DE that eventually clumps enough to bridge the gap.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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