They are rock solid, I am very pleased. Also, I do not know if you read in my past thread about the fiberglass resin I used with the sand but I did a small 1/8" layer on the tank bottom then coated with sand. After it cured I put about 1" of sand on top. The rays still dig it all up but they tank does not show a bare bottom. The sand on the bottom is a touch darker but still looks nice. You can see how it looks in some of the pics because I took them before I smoothed it back out. You can really see how it looks in the pic with just the male flower. They pushed all the sand to the front so the whole back side is bare.
