I just replaced my old 36 sq. ft. DE filter with a new 48 sq. ft. filter. I kept the same 3/4 HP Hayward Max-Flo pump, but replaced all of the plumbing. I've got a couple of questions, but here are the pictures of the old and the new:
When I used to open the old filter for cleaning, all DE was stuck to filter grids and there was almost no free DE in the filter. With the new filter, only about top 1/4 of the grids has a layer of DE, and the rest is at the bottom of the filter. Is this OK? Does it mean that the pump is under-powered for this size of filter? All the plumbing in 1.5".
The pump has been off. This morning I opened the air bleeder valve on top of the filter and a cloud of DE came out of the main drain and the skimmer. I do not have a check valve between the pump and the filter. Is this DE draining back to the pool the expected behavior without a check valve, or should DE not drain back even without the valve, meaning there is something else wrong with my setup? Is the solution to put in a check valve? Does this problem also have something to do with question #1?