I have a cartridge system. This will be my fourth season. I'm going to convert to a sand filter as soon as I go thru a baquacil to chlorine conversion.

A cartridge filter does filter out finer particles than a sand filter does. My experience has been that cartridge filters work real well when they are new. However, it does not take very long for them to quit working as effectively. This might be more a function of baquacil than chlorine as baquacil is known to clump up as "goo" on the filter. I even use the skimmer basket socks to minimize junk getting to the filter.

I've not had any luck in "acid" cleaning the filters to remove the "goo" - its an environmental mess and it's never been effective. The filters are expensive to replace - my local dealer is selling them for about $170 although I have usually got them in the past thru mail order for $90 to $120. I've averaged 2 to 3 a season. I've washed the filters down quite often, from daily to maybe every 3rd to 4th day - again more often as the filter has gotten older or after a heavy rain - I'm under several oak trees - to clear the pool up over several days.

I've never had much luck in getting my pool 100% clear - maybe at the most 90% or so, so I'm going to try a sand filter. I'll keep the cartridge as an alternative for maybe fine tuning, and let the sand filter do the majority of the work. Others might have different experiences.