Automatic Litterbox Central

I have 2 cats, one is a large senior who has always peed excessively large amounts. i gave up on the scooping litter because by the time i cleaned it, half of the box would be a solid clump and was so gross!!!

i LOVE my scoopfree, but one of the them (i'm thinking harley, the older one, gui is only a year and a half) keeps pooping in really obvious spots, i think because the crystals are getting soaked so fast. i changed the litter on friday completely and had to again this morning. it was way beyond just moving the crystals around. i put a paper towel underneath the garbage bag i use (so i don't have to keep buying the 'cartridges')and it was SOAKED!!

i really don't know what to do, is there a crystal litter that is possibly more absorbent than the fresh step? please help, i'm drowning here!