Your filter owner's manual may have some cleaning suggestions. My Sta-Rite lists Filter Cleanse (Great Lakes Biochemical Co.), Filter Kleen (by GFC Chemical Co. and also by Haviland Products Co.), Spa Cartridge Filter Clean (Leisure Time Chemical Corp.) and KLEEN-IT or Kwik-Strip (both by Biolab, Inc.) as acceptable for degreasing and scale removal when the hosing technique isn't enough. I don't know if they'd be appropriate for the material that your Pentair filter is made of.

I've also heard of the automatic dishwasher detergent solution. I haven't had a need to use anything other than a hose as yet, so I can't personally vouch for it.

Mas985's idea of a garbage can is right on. If you get the right size and the one with a lid, it can function as your storage device for your second set of filters, if you opt to go that way. I'd like to have a 2nd set, but my replacement filters are too pricey for me right now.