The main issue with the rimless for me has been fish carpet surfing. In fact 95% of the fish I have lost has been bc of this so I built a mesh top. The other b]problem I had with my old rimless is the nerite snails leaving the tank. To combat this I got some velcro to fix on the tank and top. said:I had nassarius snail commit suicide that way too. What did you get that top? It looks very clean.