Im going to try my best and explain the pictures. I drew them out and took pictures =o)
If something is shaded it means it is behind something.
The bottom frame consists of 2x4's. The corners and middle posts are 4x4's. I want my tank to sit inside the frame because the color won't match the tank. So at the top it is exactly like the top frame but instead of it lining up with the top of the 4x4 corner posts it is raised by 2in or so. Now, there are 2x4's directly under the top ones.. but ill explain that with the top view-
Okay, there are 2x4's under the top frame which will also support the tank. But they will most likely be supported on the sides of the 4x4's.. my pencil points them out-
and two more on the other side.
Now those boards and the board in the middle will support 2x6 planks that go all the way across.
I did a lot of calculating and it all works out with the measurements and proportions n stuff.
I feel like im going over kill.. or not over killing enough. Does it look alright or are there major flaws? I will answer any questions about the plans. Keep in mind Im a 20 year old college student who has failed college algebra twice =o) Im mighty proud of myself coming up with these plans, im just worried about it being stable enough to hold a 75gal. Uhm... oh, everything will be jointed together with either angle brackets or screws/nails. But yah *twiddles thumbs*