Hey guys I have 5 Clown loaches in my 40 gallon (I know they get big I can upgrade when that happens). When I had them in my 15 gallon planted tank they were darkly colored. I moved them to my 40 gallon which has pool filter sand and they seem to have been washed out ever since. They still eat tons and are always out and act the same its jut their colors are no longer dark. More like a grey color. Any idea why?