101g??? Dude, that is so not a paradise :-) Personally I'd go 36x36x20
20" height is nice. 18" is a little weird to me... not quite shallow, not quite tall ? Not that 20" is tall, hehe. Mind you, any depth we give our tanks is pretty much "shallow" compared to what the inhabitants are probably used to in the wild (save for those tidal pool critters I suppose).
Anyway.. congrats on the sale of the house! Looking forward to seeing your thread title change again soon!
