DE Powder only covering partial amount of filter???

[bigdog225]

Helping a friend. No apparent air leaks. What causes this? The remaining powder looks like sludge in the bottom of filter housing.

 

[Richard320]

I think it's supposed to do that, sort of. The infomercial for cellulose shows it happening in a clear filter housing. In theory, the coating gets covered with dirt and silt. Then it slumps off. When the filter restarts, the heavy stuff settles to the bottom and it recoats itself with just the DE. About 1:55 on this video.