Bests & Worsts Reviews from Amazon

Used to be four to five stars; the purple litter trays seem to work best, but are also the least available for some reason. Recently we received a three pack and we've already gone through it in less than a month. Waste of money, as the trays used to last at least 10-14 days, without any odor. Within days of changing everything out, the trays smell and the litter crystals are a very weird color. The formulation appears to have changed significantly and are no longer effective. We have used this system for over 4 years.