yeah that sucks the first ten hours i had mine it stayed then moved for two days and within in that two days it got sucked in a powerhead, but it didnt do any damage that i saw.and it moved to the underside of the rock and hasnt moved... im happy about that
Looks pretty good. I especially like the big RBTA as a centerpiece. If it were me, I'd add some sort of backing to the tank to force viewing of what's in the tank instead of what's behind the tank. Other than that, not too shabby.
I think it would be fine to take out 1/2 of the water, paint the back and put water back in. I have know and or done my self to paint with a spray can, brush or a roller. All methods work but some require more work and longer wait time but all come with same results. Good luck.