Cellulose Filter Media Keeps Clumping

I have been using a cellulose fiber filter media with my Pentair FNS Plus 48 DE filter, when I go the clean the grids a lot of the media material is clumped toward the top of the grid, and the coverage is sparse on the lower part of the grids, the directions say to add 3 cups per 12 feet of filtration area (12 cups) directly to the skimmer, i saw an earlier post that mentioned adding it as a slurry. i am wondering if this could be why the media is clumping and effecting the performance of my filter?
 
I wonder if you've had air trapped in the top and thus, less water turbulence inside?

I add cellulose a cup at a time and it swirls around in there and I have to mix it up with my hand to get the last of it to go away before I the next cup. So it ends up as a slurry anyway. I can't imagine it flowing into the filter in a clump. It has to get through the mesh on the pump strainer basket and then get beaten up by the impeller first.
 
Richard, I agree, but when I remove the manifold to clean the grids their are clumps (or build up) of filter media on top and between the grid assembly, and minimal to no filter media on the lower portion of the grids. When I do add the filter media I do it like you mentioned, one cup at a time and I make sure the filter is pulling full prime, making sure I don't have any trapped air. Just has me perplexed.
 
After using cellulose fiber for a year, I went back to DE. I was a big fan of the fiber filtering ability and that its biodegradable. Then I went just a bit too long between backflush and recharge. I broke down the filter and found that the fiber was becoming a gummy mess. I started thinking that I try so hard to keep organics out of the pool and here I am adding an organic material in the filter. It seemed that the chlorine had started doing what it does to all organics, it was breaking it down. So my biodegradable filter material was breaking down and that of course was beginning to consume some of my chlorine. I guess the fiber is as good or better than DE at filtering, just be sure that you backflush (or better yet do a breakdown cleaning) of your filter very regularly. Could this phenomenon be what the OP is describing as clumping?
 
1.I conducted a test over the past three weeks on my Pentair FNS Plus 48 DE Filter trying to eliminate the clumping and grid coverage issues that I talked about in an earlier post. I added the filter media as directed on the packaging - 3 cups per 12 feet of filtering area slowly through the skimmer, I let it run for a week then pulled the grid assembly. There was filter media all clumped underneath the grid manifold and did not evenly disperse throughout the filter grids.

2. The second test I added the filter media as a slurry through the skimmer, let in run for a week, pulled the filter grid assembly, although their was some clumping at the top of the filter grids it wasn't as much as the first test and the distribution of the filter media, though not full coverage on the grids, was better.

3. My final test, I dissolved the filter media, added it through the skimmer, and again let t run for a week, pulled the filter grid assembly and there was no clumping anywhere on the filter grids and the coverage, again not complete but was the best of the tests. I don't know if I am the only one having the filter media clumping (or building up) on the upper portions of the grid assembly, but it seems dissolving the filter media gives my better filter coverage and no clumping.

4. There is one thing I noticed out of all three of the tests is that the air bleed tube that attaches to the top of the filter manifold becomes clogged with filter media, so after a day a running the filter I remove the lid, clean the screen on the air bleed tube. Don't know if this is normal as I could not find any information on it and nothing in the owners manual either.
 
I have the same filter as yours, I use 9 cups of cellulose after im done backwashing..... recommended by my pool builder.....

Do you think you might not be adding enough (3cups) and that why you are seeing those results on your filter?
 
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