DE Filters - Lesson Learned

[rhosk]

When I opened my pool this year, I decided to "try something different". My DE filter was, as usual, cleaned before putting it in storage last fall. When I put everything together and started my pool clean up I thought that I could get away with not adding DE powder to the filter until I really needed it (assumed it would only filter the 'smaller particles' anyway). When I got the bulk of the pool cleaned, I figured I could then take the filter apart, hose off the accumulated scum, then start fresh. I couldn't figure out why the filter pressure was jumping 10-15 psi in about 10 minutes - backflush 30 seconds, all clear - 10-15 psi jump in 10 minutes I mean, at first I thought it was just a bunch of algae/scum from the initial pool opening and it was rapidly clogging the filter. I even went so far as to call the local pool stores to see if they had my filter grids in stock because I started thinking that maybe they were just worn out/clogged to begin with. Thank goodness they weren't in stock or I surely would've purchased all 8 of them. I took the filter apart and inspected the grids once again. They show minor signs of wear, but nothing obvious visibly. Hosed them off a final time and put it all back together. Decided (for whatever reason) to add the DE powder this time. The pressure miraculously reduced a few p.s.i. and maintained that pressure for hours!! I was flabergasted. How can adding this powder to the filter not only reduce the pressure, but maintain the pressure better than without (rhetorical)? I don't understand the theory, but just know that it requires the powder to work effectively. And I think the initial DE that's added to a fresh filter is called "staining"?

If you're a pro, then you probably understand why all of that happens, but if you're a novice like me, and you searched the forum for 'pressure problems' with a DE filter, then I hope it helped you.

[imfignewton]

Here is a web site with information on DE, cartridge and sand filters.

http://www.poolcenter.com/filter.htm

[edarling]

I thought the same thing this year. I figured I was vacuuming to waste, mostly, but I did run the water through the filter w/o adding DE just for a short time (hour or so in green pool). When I was done, I decided to add DE my usual way - through the skimmer. Well, the filter was so clogged that the DE would not get pulled into the filter. I had to disconnect the filter, take it apart (a big pain on those 15 bolt Hayward filter), soak in muriatic acid to clean fingers, then add the DE into the tank, and restart. I also broke a really old piece on my filter housing, which took 3 stores to get - a piece that is not readily available because it was so old.

To get the DE out of the lines before reconnecting, I had to use my shop vac and blow out the water from the skimmer to the connecting to the pump housing. What a big project. It cost $80 to fix the filter, since taking it apart broke an obsolete piece and the replacement was 3 parts together in a kit that the dealer would not separate b/c it was so old.