I heard I needed 1 1/2-2 pounds of gravel per gallon and I have a 28 gallon so I bought 50 pounds of gravel. It's about 3 inches thick in my tank, l: 30 w:12 h:18. Is that too much? I'm keeping 8 Panda corys, 12 Neon tetras, 1 Rubberlip pleco and 2 honey Gourami. Will they still have space or should I take some gravel out?