Tucson Reef
New member
I would personally not use two different substrate sizes together. You could get poorly "sorted" sand. This is where the lack of uniformity between grain sizes prevent the flow of waste, gas, and water through the sand. The smaller grains of sand would get trapped between the larger grains of sand and basically block your water flow. Just my 2 cents
It actualy gives you a better sand bed as the natural settling fills in the gas areas , so you have a nice even bed of healthy bacteria. I also gives it more stability against sandstorms.
