Should be. If you want to be doubly sure of your uprights staying 'true' do a triangle insert on either side of the joint just a triangular shape cut by cutting a square of 2x4 diagonally in half. This way you've got 6 nails stabilzing that joint instead of 2. And I would not do just 4 uprights (at corners). You need two or three supporting your doors, and sufficient braces on the back side of that 6 foot run. Liquid Nails on those joints couldn't hurt, in addition to the regular steel ones. Note: I tend to overbuild, but likewise I don't have things warp out and skew---I am NOT a carpenter, understand, but I've gone a lot of household remodel. One item that worked super well for me: I got a piece of preformed kitchen formica countertop that serves well for a rimmed and utterly water and chemical proof top that gives me a little 'lip' for my tank (in this case my sump, which is freestanding in the basement) and lets me set test materials and whatnot down. If you have a freestanding sump, it is a very good, easy top. Wouldn't advise it for the main tank, however: sleek is better.