My 125g is also the same framework... also built with 2x4's. You cant really see it, but the corners are each 2 2x4's screwed together in an L pattern for side shear strength, as well as front to back shear. I use only screws in the main structure. Here are a couple pics of the 125G stand.. same framework, with the exception of an added front brace.. I was not going to go a 6 foot span without one. The one for the 75g only has a brace in the back center... but it is strong.. I could park my car on it.. lol
Same basic frame as the 75g... :
Hope this helps... and remember... USE SCREWS. This stand cost me about $100 to build.. the one for the 75G,... About $25.00... double it if I had of sheeted it. and remember.. Stands MUST be square and level, and strong enough to park a car on.. lol
The stand pictured weighs about 250LBS finished.. The 75g stand weighs about 50lbs or so..unsheeted
Jason