Filter delivers dirty de

[FRANCIS]

I looked at Pentair's Quad DE / cartridge filter user manual. it says a brief cloud of dirt is characteristic for diatomite filters. Maybe i can incorporate a motorized valve that reverts discharge water back into the return for 10 seconds during start-up.
http://www.pentairpool.com/pdfs/178658EQuadOM.pdf

[SunnyOptimism]

I looked at Pentair's Quad DE / cartridge filter user manual. it says a brief cloud of dirt is characteristic for diatomite filters. Maybe i can incorporate a motorized valve that reverts discharge water back into the return for 10 seconds during start-up.
http://www.pentairpool.com/pdfs/178658EQuadOM.pdf

Hey @FRANCIS, how are you? Did you get a new DE filter?

Yes, I have a QuadDE filter and I can confirm that it does that but only for a short period of time after initial start up, deep cleaning or backwashing. This past fall, I completely tore down my filter and cleaned out all the old DE from inside the filter body and from the cartridges (takes about half a day). I then restarted my system and performed a full DE recharge (about 10lbs of DE or 20 plastic scoops). For a few weeks after the restart, I would see a cloud of DE come out of the returns for no more than 30sec or so. Basically what is happening when you clean the filter is that you remove all of the DE from the nylon fabric mesh of the cartridges (backwashing partially does this as well). Then, when you start using your filter, it takes time for the DE/water mixture to build up a coating on the fabric surface. Eventually it does and over time the DE eventually gets stuck in place on the nylon and no longer falls off when the pump is not running. It took about a month, but the DE gradually stopped coming out of the returns and I no longer see it anymore during pump start up.

Here's the trick to maximize the likelihood that the DE coating stays stuck - when recharging the DE after a tear down clean or a backwash, add the DE back very slowly and only 1lb at a time. Take a a 1lb plastic scoop, add the DE to a 5 gal bucket of pool water and mix it up to a slurry. Then pour the mixture very slowly into the skimmer. After that, wait a few minutes before adding the next pound. It also helps if you have a 2-speed or variable speed pump to run it on the highest speed so that you are operating at the highest possible flow rate. DE has a tendency to settle out of water fairly quickly and you want the DE to hit the cartridge material not just settle to the bottom of the filter tank. Using the slow add procedure will maximize the amount of DE that gets embedded into the cartridge and reduce the DE blow back.

If you constantly see lots of DE coming out of the return or it takes longer than a few minutes to stop, then there could either be a hole in one of the cartridges or something is loose and not seated properly.

[FRANCIS]

no, i did not get a new unit. especially after reading blowback is normal. the methods you describe take patience. i have a limited amount of patience. i need fast results. i will probably try the non-diatomite media this year - you know - the fiber stuff. if that fails, i will see if i can scrounge up a recycling valve [motorized].

[JimK]

Hmmm....I never noticed DE blowback with my Hayward Pro Grid 6020 DE filter (installed in 2004) even after a backwash/recharge.

PS - After backwashing, per Hayward manual, I do run it with the multi port valve in the Rinse position before returning to the normal Filter position. Perhaps this is why I don't get any DE blowback in the pool?

[SunnyOptimism]

no, i did not get a new unit. especially after reading blowback is normal. the methods you describe take patience. i have a limited amount of patience. i need fast results. i will probably try the non-diatomite media this year - you know - the fiber stuff. if that fails, i will see if i can scrounge up a recycling valve [motorized].

You might be happier with a cartridge filter - no DE or Fiber to recharge and you get slightly better particulate performance than a sand filter.

Hmmm....I never noticed DE blowback with my Hayward Pro Grid 6020 DE filter (installed in 2004) even after a backwash/recharge.

PS - After backwashing, per Hayward manual, I do run it with the multi port valve in the Rinse position before returning to the normal Filter position. Perhaps this is why I don't get any DE blowback in the pool?

That could be it but I will say the effect is very hard to notice unless your looking right at the returns when you start the pump. It kind of looks like light-grey colored water coming out for a few seconds.

I also think that this is a consequence of the Pentair QuadDE design as it is basically a quad cartridge filter that has modified cartridges that a capable of holding DE. It is not the old style finger-type or vane-type DE filter. It's actually a really nice design as it is super-easy to take apart and the cartridges are pretty robust. Also, if you get tired of DE, you can convert it easily to a cartridge filter.

That being said, once you recharge the DE, it only takes a short period of time for the blowback to stop. At least that has been my experience it after three season.

[FRANCIS]

I overhauled the DE filter and found no tears etc. But I had three grid fingers with slight miudpoint weave damage which I wrapped shut with electrical tape a few years ago. So this time I decided to replace said fingers (3) and now I get no blowback. (at least not yet) There is no way so much dirty DE could have snuck under the tape. I am at a loss to explain this issue any further. Although there is one thing I learned in life, when you can't seem to figure out the problem with a mechanical device, overhauling it seems to do the trick.