DE filter problem: was question about media

[Beez]

I switched to cellulose from DE at the beginning of this season. Overall, I'm very pleased with the decision, but there are downsides to fiber in my experience. For one, my filter clogs much more frequently with fiber than with DE. With DE I would backwash pretty much 2 times per year. Since changing to fiber I have cleaned the filter 3 times now, and we haven't even gotten to the Autumn Deluge yet.

Which brings me to the next "downside" IMO. With DE, I could backwash the media from the filter good enough that only yearly breakdown would be needed. Some here on the board will be familiar with my "experiment" whereby I went 4 years without breakdown. I don't believe this is possible at all with fiber no matter how much backwashing you try. The fiber clumps into very thick mats and sticks there. It comes off easily enough with a hose, or with your hand you can pull off the clumps, but backwash won't budge it.

This last part is what leads me to post this thread. For those of you who have switched like I have, do my comments approximate your experience with fiber? I just wonder about those clumps... I wonder if they were deposited by the minimal backwash I did, or if they were deposited when introducing the media to the clean filter? If it's the latter it seems worrisome to me. Seems like the media may not be coating the grids as evenly as DE did.

Maybe I think too much, as the pool water is very clear and seems to sparkle every bit as much as it did when I used DE. It's just those clumps...

EDIT: I forgot to add a very important point! The reason the clumps worry me is that the fiber does not raise the filter pressure at all when recharging. I verified this yesterday. Clean filter pressure with no media = 10psi. Filter pressure after recharging with fiber = 10psi. Significant? Recharging with DE always raised clean pressure by at least 2psi...

 

[Bama Rambler]

Re: Fiber alternative to DE query

That is an interesting observation and hopefully more people that are using cellulose will post their experiences.

Have you opened the filter right after charging to see if the grids are getting coated properly? It would be great if there was a way to get a camera in there to see what's happening.

 

[Boland01]

Re: Fiber alternative to DE query

I'm using DE but have kicked around the idea of switching to fiber. Knowing the pro's and con's plus the opinion of those that have switched from one to the other would be great.

 

[Beez]

That is an interesting observation and hopefully more people that are using cellulose will post their experiences.

Have you opened the filter right after charging to see if the grids are getting coated properly? It would be great if there was a way to get a camera in there to see what's happening.

I agree that's the only sensible way to know what's going on. Removing the filter lid is not my favorite chore, however. Maybe I'll buck up and take a look under the hood this weekend...

 

[Beez]

Ok, so I took my own advice and removed the filter lid to observe the filter media on the grids. There was media only at the top of the grids, clumped up just as I described. I thought, AHA! caught you!

I have DE still, so I decided to disassemble the grids, spray them off, then try DE to see how it worked. Removed lid a second time, and ****! No media on grids!?! What am I doing wrong??? I made double sure to purge all air from system the second time. Is it possible that removing the lid causes the media to fall off the grids, especially where DE is concerned? Maybe I didn't wait long enough before removing the lid the second time?

 

[Bama Rambler]

Re: Totally STUMPED!!! Please help!

I suspect it falls off when new once you stop the pump. That's why I'd like to see it with an inspection camera inserted while the pump is running.

 

[Beez]

For the record, this is what I saw when I removed the lid the first time. (I have other pics, but this one pretty much sums it up.)
[attachment=0:1ee8onvn]grids with fiber.jpg[/attachment:1ee8onvn]

 

[Beez]

As the title says: I'm stumped as to what to do next. My filter is apart at this point. Don't know if I should recharge with fiber or DE... Also, suspecting my process at this point... Anyone have any ideas?

JAT...the only thing I have did differently the last two times was remove the pump strainer basket while I recharged the filter. Could that have caused the problem? The reason I did that is that the last time I cleaned/recharged the filter(couple months ago) I noticed the cellulose was having some trouble moving past the strainer basket...or so it seemed...

 

[mu22stang]

Re: Cellulose vs DE blah blah

I have an FNS Plus 60 and use Zeofiber. When I've pulled mine apart for a cleaning, it does clump at the top and bottom similar to your pic, but I still have a uniform distribution across the filter grids as it should. I do not pull the pump basket, only the skimmer basket. My pump pressure rises a maximum of 1psi after an 80% post-backwash recharge. It's usually closer to 0.5psi rise.

How long do you run the pump after a recharge? I usually let it run for 2 hours or more to make sure it distributes on the grids.

How long does it take you to add the cellulose? I add a scoop every 30 seconds or so, very slowly. I have the water hose in the skimmer at the same time to help break up the clumps, refill the water lost in backwashing, and distribute cool water into the pool.

 

[Beez]

I have an FNS Plus 60 and use Zeofiber. When I've pulled mine apart for a cleaning, it does clump at the top and bottom similar to your pic, but I still have a uniform distribution across the filter grids as it should.

So the media stays on the grids even after you remove the lid?

I do not pull the pump basket, only the skimmer basket. My pump pressure rises a maximum of 1psi after an 80% post-backwash recharge. It's usually closer to 0.5psi rise.

How long do you run the pump after a recharge? I usually let it run for 2 hours or more to make sure it distributes on the grids.

How long does it take you to add the cellulose? I add a scoop every 30 seconds or so, very slowly. I have the water hose in the skimmer at the same time to help break up the clumps, refill the water lost in backwashing, and distribute cool water into the pool.

I always run the pump several hours after cleaning/recharge, and add media(fiber or DE) in a slurry, poured slowly into skimmer. I always purge the air out of system before recharging.

I'm totally confused now as to how a DE filter works. I always thought once the media coated the grids it stayed there until it was hosed off. I don't understand how it works if the media falls off the grids even partially at any time. I believe either I'm doing something wrong, or there is something wrong with my setup. Regardless, I'm stumped. I searched the forum and found where a couple of others had a problem similar to mine, but interestingly there was no definitive solution in either case.

 

[Beez]

FWIW, that was Zeofiber in that pic above. Here's another pic that clearly shows no media coating bottom 2/3 of grids. I really don't believe it fell off either. The "clumps" you see at the top were very thick. Look at the top left of the pic where I bumped that mass with the filter top.[attachment=0:x7s3is06]grids with fiber 2.jpg[/attachment:x7s3is06]

 

[Beez]

Ok, once again I have aired my foolishness publicly, but I update this thread so that if anyone finds it later in the archives it will have a resolution.

It all started with a fundamental misunderstanding of how a DE filter works. I was under the assumption, erroneously, that under normal operation the media was supposed to coat the grids and remain there. That is exactly opposite of correct. Adherence of the media to the grids is the abnormal condition. Under normal operation the media falls off the grids once the pump is turned off, then re-coats them when turned back on. So my initial idea to inspect the grids after recharging was faulty from the start. No can do.

To an extent, my experiment was a total loss of time and energy. However, it did lead me to one important discovery in a graphic way. Turns out, too much cellulose is not a good thing and is probably why I saw the clumps as I did (as well as the more frequent pressure rise...DUH). In short, I was using too much product. Especially with fiber, but I'm guessing with DE as well, it is better to err on the low side when recharging. It is ok to experiment with using a little less media, but the overall lesson here is whatever media you choose DO NOT OVERCHARGE. Oh, and curiosity killed the cat...

Ahhh...another Beez epic mystery solved. Baffling...just baffling...


Better not let the higher ups in Inverness hear about it, else they'll be sending me to Glasgoo...

 

[Boland01]

I've learned from experience to go on the light side with DE too. Especially when I backflush.

 

[mu22stang]

This makes quite a bit of sense. I'm relatively new to pool ownership, though I did spend a summer home from college cleaning and balancing pools with a friend. I bought a house with a pool in April of 2011 and have learned quite a bit since then. I knew I'd have to learn how to do a full filter break down at some point, but I don't recall if the circumstances required it the first time I did it (~Fall '11). I went to the store to get DE and they recommended the Zeofiber because I was complaining of itching. I guess some are more sensitive to DE. My hands and feet (I wore sandals) were going crazy for days.

I've done two filter breakdowns since then and this certainly explains the frequency of break-downs, pressure rises, and apparently "abnormal" coating. I would backwash, recharge and see the pressure rise again within 3-4 days. Backwash, recharge, repeat until I'd break down and tear the thing apart yet again. I'll start experimenting at this point - perhaps tapering off the addition of cellulose more aggressively as the backwash cycles become more frequent, e.g. 80% post-backwash recharge, 60%, 40%, etc.