So I'm planning on setting up a semi Walstad method tank. Can I use 2 inch sand or more on top of the soil? I'm still planning on using a sponge filter, I'm just learning about the Walstad method and incorporating it to my tank to help me with filtration and plants and stuff. I'm adding a thick layer of sand in the back section cause I have a scape in mind that I'm planning to do. It's a 5 gallon cube and I'm only planning to use it for shrimp. Also is there any common mistakes I need to avoid?