I have taken on the responsibility of taking care of a neglected 125 gallon for a local business. The tank houses 9 frontosas and a few other cat fish and algea eaters. The owner wants me there once every two weeks to maintain the tank; water changes, filter checks, etc. I'm looking for ideas/suggestions on what to use for substrate and shelter/hiding areas. Currently they have black gravel mixed with white silica sand and large clay pot cylinders for hiding. Any input, pictures, links, etc. will be very helpful.