Thanks. Here's hoping it doesn't cloud the water too much. I read about a trick of making flat packets of litter wrapped with waxed paper. easier to lay as a foundation in the tank (this one is only a 20 gal high). No ill affects from the waxed paper noted. I have a fine sand substrate now & plan to add a coarser overlay. I'll let you know if the waxed paper method works. Next project is to boost the lighting to satisfy the needs of a planted tank. That one should take a chunk of $'s compared to kitty litter.