Hi, and welcome to the forum!!

I'll let some of the cart filter folks comment on your cartridge questions, but I can say from a sand filter owner standpoint, sand filters are pretty much non-maintenance, except for an occasional backwash. I don't close my pool over the winter, so backwashing and occasional replacing of the spider gasket is the ONLY maintenance I've had to do. You backwash the filter when your pressure rises 6-8 psi over it's "clean" pressure. While actually backwashing the water, it needs to run until the water in the sight glass clears up, usually 2-3 minutes. Then you switch it to "rinse" to rinse the stuff remaining in the pipes out, which takes about another 45 seconds to 1 minute. Then you switch back to "filter" and it's all done!

If you ever have to fight algae blooms, a sand filter will be much easier to deal with than a cartridge. Also, our other 3 mods, who also have sand filters, use a handful of DE in their filters to actually give the sand filter the ability to filter as well as a DE filter.