I used to keep clown loaches in regular, dark colored gravel in my 55 gallon tank. My clowns seemed happy. They would even pick up the gravel with their mouths and make a pile. I later moved them into a 125 gallon tank, with smaller gravel. Sometimes when the clown loaches would take off quickly, the water would disturb the substrate, which would eventually uproot the plants. I found out the it's best to use eggcrate on the bottom of the substrate when using loose substrate with CL's. This way, when the plants grow out and spread their roots, they would eventually root themselves onto the eggcrate.
