DYI Stand Plan, how is this idea?

[daplatapus]

Monocus is correct. With a 75 gal, 48" tank, 2X4 is fine. But being a contractor and seeing literally 100's of studs a week, I certainly would want to personally chose those that I would use. I can't believe the crap their allowed to sell.
I would also lose the Blue joist as it's really not necessary and just complicates the design.
Just make sure when you're laying out the joist spacing that one isn't where your holes in the tank are. And keep the joist to no more than 16" centre's.
I personally don't like using pocket screw for anything structural. If the stand is being skinned or covered in any manner, those screws will be hidden anyway. In any floor joist application, if you can end nail ( through the rim joist at 90 degrees into the end of the joist) you don't need hangars.
As far as doubling up the front rim joist, it potentially has it's merits. In the back, you're more than likely going to skin it or even put a stud midspan to help carry the weight. But in the front, if you have a sump, you may not really want anything preventing you from slipping a sump in there or at the very least have a support that's removable so you can do so. The limit there though is (if that's why your putting it in there) you really shouldn't remove it while the tank above is full. It's only on set up, before the display is filled, that it can theoretically be safely removed.
In this case, a stand builder may decide for extra insurance, and to help strengthen that front support, instead of putting a stud mid-span, to double it up.

[monocus]

in the back i put studs every 16 inches,but i dado them out so they are removable and can be easily be replaced.the double joist in the front helps carry more weight if you are putting doors on the front of your stand

[Easto]

Sweet, makes sense. Thanks for the help.

[coolhandgoose]

Spend lots of time picking your wood. Look for cupping, warping, twisting. If you have a table saw, run it through one side, then shorten the fence and run the other side for more square edges. 2x4s tend to have rounded edges. Check out the beginning of my build thread to see what I did.
Good luck!

[Duckhams]

Im definitely not going to dissuade you from over building it, a strong stand is a good stand, but this is one I built a while back and it was seriously over built. Remember that most commercial stands are only plywood, and they hold up. Some well chosen, straight (as best you can find) 2x4's and you'll be fine. You have a solid start there (no pun intended).
I should note that the final build had a center brace in the back and one in the middle of the top surface. I used a 1/2" plyboard top and bottom which really made it solid, and skinned it with 1/4" ply.

[Easto]

I want to do the top, front, back, and sides in plywood. Maple or birch depending if I'm staining vs painting.

What thickness do you recommend?

Screw the plywood or nail it?

[reefwithareefer]

The only 2 cents i will say, is that you may want to consider fir 2x4s and not spruce. Fir is much less likely to deflect

[Duckhams]

Originally Posted by Easto

I want to do the top, front, back, and sides in plywood. Maple or birch depending if I'm staining vs painting.

What thickness do you recommend?

Screw the plywood or nail it?

1/2" on top is more than enough. If you're using the 2x4's then 1/4" sheets on the back and sides are easiest to work with and keep the weight down. Screw the 1/2" down and use finishing nails for the back panel. Either could work on the sides, depending on what sort of style you're going for.
Add a good coat of KILZ waterproofer inside and seal the inside panels (at least a couple of inches up from the bottom panel)to prevent water leakage/damage later on. This will save your floor too. No matter how hard you try something will spill, overflow, splash etc.