..........INCHES..........length.....horizontal depth.....vertical height 30 gallon 36 12 16 30 gallon breeder 36 18 10.7 40 gallon long 48 12 16 I like the depth of the 30-gallon breeder, but it's only about 11 inches high which isn't enough room for plants. I like the height of the regular 30-gallon, but I miss the depth that 18 inches of depth really adds a lot to an aquarium.. I don't really want to go to 40 gallons, because the extra 100 pounds worries me since the tank will be on the second floor upon a non-load bearing wall. Also, I have (will have) my desk next to it. The desk weighs 200 pounds and my fat body also weighs 200 pounds (errr, well, in 2 weeks it will weigh 200 pounds). So I have the tank on my left, and the desk at a right-angle to it, choosing to distrubute the desk and *my* weight over the load-bearing wall joists. (I think I'm getting off topic here). (load-bearing wall along this direction with the joists running from the top of the screen to the bottom. Tank Desk _____ _________ | | | | | | |________| | | me | | _____| anyway, ever thought which is nicer, the regular 30 gallon or the 30 gallon breeder? Or maybe, what is your favorite size tank that isn't too large? I really like the 40 gallon tank, for example, but........well, I'm blabbering. better stop typing now before I bring up politics or something.