If you have the money for a rack now buy the biggest one you can. Not saying you need to fill it now but if your looking to add to your collection once you goto college you might as well have the rack before hand. I'm just a poor college student who wishes back when I had money before I moved on my own I bought two 4 tub racks but that's just me. Do what makes you happiest in the end two tanks isn't alot to clean if you go that way but at times it can be more of a chore cleaning two tanks but you can make them look prettier.