I have two 5 year old cats (adopted at 6 months) and we use 2 litter boxes side by side. We've always used pine pellet litter and the cats are fine with it. Never had a problem with poop smell, even when I forget to scoop, but the urine smell seems to get bad quickly. I think part of the problem is they tend to pee mostly in just one of the boxes. I don't use any type of system - just litter in a tray. We do a full clean out once a week (saving some of the pellets that remain) and scoop the rest of the time. Anyone have a good system that they use with pine? Trying to keep costs down too. Thanks!