I've had a problem that has not affected my pool-clarity, so I've essentially let it slide. However, the more I read the forums, the more I'm concerned by the issue and if nothing else, figure I should at least understand why its happening.
My DE filter (Hayward ProGrid 24 Series, the DE2420 Model) is behind a Pentair Whisperflo pump (2 HP). It has the matching Hayward Six-Position Vari-Flo multi-port valve. These were all purchased new and installed about 3 years ago.
The pump has about 80' of head (if you consider all 90's, etc).
The reason for the fairly large pump / relatively small filter (the 2420 is the smallest, with only 24 sqft of filter) is because it powers our swim-spa (about 1,000 gallons). Therefore, even the 2420 is overkill; however, I think the 2 HP pump could possibly be pushing too much for this filter? I have no intelligent basis for that claim, simply a concern over the issue I'm about to explain.
When I first went to coat the filter (adding DE through the skimmer) I followed instructions. I carefully weighed out the DE, and put in the specified amount. Prior to the DE going in, pressure was about 29 psi. After the DE went in and equalized, pressure was still 29 psi. When the filter pump is off, pressure drops to 0 psi.
After 6 months of use (only gets 3 hours of recirc a day) pressure did not change, zero difference. I decided to let it continue filtering. At one year, still no rise in pressure.
At one year, I backwashed, removed the grid, and inspected everything (not really knowing what to look for, but it fit snug and there were no rips). Again went through the coating process, and received the same results.
29 psi before any DE is added, against a clean filter. 29 psi after DE is added. Doubled-up the DE (twice specified amount) and I still get 29 psi.
One year later, did the same thing (opened, inspected, replaced) -- same results.
Everything I read says that 2 minutes after adding DE into the skimmer, the DE filter's pressure should rise noticeably. What am I doing wrong?
I should also mention, the filter appears to work very well. I've had my pump stop while away on business, return to a pretty rough spa, and it will look crystal clear in about 6 hours with the correct chemistry.
Every now and again, when the filter is first coated (after adding DE) a little may escape into the spa, causing me to thing there is a very small leak. However, this is a very small amount and it's only when I first coat the filter, possibly the first 3 days or so after coating.
Thank you in advance