If you have enough filtration then having a bare tank is never an issue. So if have a decent amount of filtration substrate isnt needed. All my tanks are bare and i havent ever had a problem with keeping levels at 0 excluding nitrate. BB will only grow in areas where theres water flow so i wouldnt worry too much, throwing in another blotch of media in the filter should compensate for the missing substrate. nice fh's btw
