I don’t know what you mean by cleaning a hard surface but I don’t think so. There are 8 in the tank. I panicked and thought it was poop hanging out so I added epsom salt. It doesn’t appear to be having issues at this point.
We have had an ammonia spike and it hasn’t gone down in the past two or three days. My husband wasn’t testing it correctly so we thought it was zero until a couple days ago. We have been doing water changes. Today did a 50% change.