First full season with DE

[phpbutcher]

Hi everybody,

I just finished my second perfect pool season on the BBB method. Towards the end of last season I switched over to a DE filter (Hayward Perflex EC50 DE Filter) and didn't notice anything unusual at closing time when I took everything apart. This year after a full season there was a considerable amount of gray sludge at the bottom of my filter. Is this normal and I should expect that at the end of a season or did I do something wrong? According to my understanding of the instructions I'm not supposed to backwash this filter at all, just bump it after I vacuum the pool each time which I did.

Am I missing something?

Thanks

 

[JoyfulNoise]

The grey sludge is basically dirty DE. I would disagree with the manual that you probably need to backwash, but it really depends on pressure rise. TFP recommends backwashing (or cleaning in the case of cartridge filters) whenever the system pressure rises 20%-25% over the clean pressure. "Bumping" simply shakes the fingers in the PerFlex filter knocking off the DE coating and letting it reform. So the DE is still basically dirty at that point and the bump lets some of that dirt get through. Backwashing actually removes some (not all) of the DE from the filter and let's you recharge it with fresh, clean DE. There will always be a pile of DE at the bottom of most DE filters as it tends to fall away from the grids/cartridges/fingers (depends on the type of filter) when the pump is shut off. The in-rush of water and initial turbulence during startup will typically churn up enough DE to properly coat the filter media.

If you had a significant amount of sludge at the bottom, I would say that the filter was overcharged with DE initially. For example, my filter (which is DE but a different style than yours) calls for 10lbs of DE after it has been fully cleaned out. However, I typically only add about 8lbs. Whenever I backwash the filter, I probably flush out approximately 50% or so and then I recharge with no more than 3-4lbs. If I added the full charge (10lbs) with every backwash, my filter would eventually just fill up with DE. As well, I tear down and completely clean the DE filter once per year.

 

[phpbutcher]

Thanks for the reply Joyfull. I feel better knowing that's supposed to happen. I got the filter at the very end of the season the year before and it didn't have time to do that so I wasn't sure.