I'm just hoping that when I measure the wall it is 18' and I can put 3 6' tanks in there!

Don't forget you probably want a doorway to get in behind them. Or I suppose you could put a little hatchway underneath the tank to get in behind, sort of like a Star Trek Jeffries Tube or something ... :lol:

I was thinking about that. However, why would I need to get behind them. My current tank is against a wall and I have never found it necessary to get behind it for any reason. Although it may be nice to have a sump room behind it, my basement wont allow for that. I will have to work from the front.