Sand Filter and Cartridge Filter Owners Please Advise

[CarlD]

So follow Ben's rule: If they recommend a certain size filter for a given pump, go up one size for IG pools and up two sizes for AGs. So, if they recommend a 150# sand filter, on an IG pool, get a 200#. On an AG pool get a 250# filter.
(there are exceptions: My pool is technically AG, but so similar to an IG and uses an IG pump that I only went from the "recommended" 150# sand filter to a 200# sand filter with no problems as I wind up 9 years with it. But recently I did some new calculations and realized that I had no problems because my filter is just over the limit of an adequate filter for my setting. It's ALMOST too small, but "almost", as the saying goes, only counts if you are tossing horse shoes or hand grenades.)

Carl

[PoolDoc]

So, if they recommend a 150# sand filter, on an IG pool, get a 200#. On an AG pool get a 250# filter.

Actually, Carl, that wasn't quite how I meant it.

What actually happens is that the 'recommended' filter size for, say a 20,000 gallon IG pool, is a 22" filter (at 15+ gpm/sft). But, due to some games the industry played with the NSF, the 'recommended' size for a 20K gal AG pool (at the 'rigged' standard of 25 gpm/sft) is about an 18" filter.

But, what you NEED for either pool is a 24" filter, which gives you about 13 gpm/sft.

[CarlD]

I stand corrected...

Carl