Hi. My last posting was sharing a catastrophic loss of all my fish while on vacation. Two years later my tank is up and running with healthy and thriving fish. Now here is my substrate question. For whatever reason in the past I decided to use a pebble substrate( pebbles a bit larger than pea gravel). I am using an under gravel filter along with my trusty sump and external bio wheel. Never any water quality issues. So is trying to switch to a traditional sand bottom a bad idea this late into the game? Besides the work it will take will the affect the sand have to the water be hard on the fish? My fish are a mix of OBs, rusties, elec yellows, coba afrues, and two large plecos. A couple other generic peacocks. Thanks.