Well, somebody has to stick up for cartridge filters...

The return flow should be unaffected by the changeover to a cartridge filter but it does seem the model you chose is a bit on the small side for a 18x36' 30K gallon pool. Maintenance can be a chore if you're having to disassemble the thing every month to clean the filter. That was the principle motivation when I selected an oversized cartridge filter (see equipment in my signature line) for my pool.

The C-751 provides about 75 sq ft of filter media for your ~650 sq ft pool. The SwimClear C4025 on my system provides 425 sq ft of filter media (and has twice the flow capacity), yet my pool is about half the size of yours.

You see where I'm going with this. I clean the filter once a year and even then it's not really dirty.


I don't eat Maryland steamed spiced crabs -- they're just too much work.