I just bought some kitty litter. Special kitty litter brand. my plan was to put about an inch of it as the bottom layer of my substrate, then one inch of shultz aquatic plant soil, then 1-2 inches of regular gravel. Now, those of you that have used this kitty litter before, how did you tell it was ok to use? I put some in a cup of water and it got kind of soft and I could then break it apart with my fingers. So, should I still use it?