Plywood top of stand how thick should it be?

I just built my own stand 40" long to hold a 30" long tank giving me 5" extra each side, problem is how thick should the plywood on top be, at present I have used 1/4" plywood but I'm scared it's not thick enough before I paint it, I used it this thin to save on weight, the tank is glass rimless with side panels resting on bottom
Thanks

 

I would put two cross beam 2x4's where the trim of the tank is going to sit before I put the wood on top. And use a higher quality plywood maybe 1/2" and seal it really well with some paint/stain or something because plywood gets soft and warps easier when its wet. Even better would be to use a nice solid plank on top instead of plywood. But 1/4" alone would scare the crap out of me if it were my tank.

 

The weight of the tank should be supported by it's perimeter. Nothing is needed in the center, and could cause more harm than good. The most important factor is to level the stand with no twist in it.

 

Thanks for reply, the top frame is made of 2x4 lumber 40"x22" plus 2 19" pieces secured in the middle, i have read that a glass tank needs no support other then the edges and corners of the bottom of the tank supported by the 2x4 frame alone, so im some what confused, if this is the case then what does it matter how thick the plywood is,

But because the stand is longer then the tank its mainly supported by the rear and front 2x4 there is no support on the right or left of tank, but i have positioned a support leg on the middle rear.

 

Thanks,
it sure is confusing, but the tank stands flat, no wobble , and the spirit level is between the lines on all angles.

 

^ +1,000- And Jerry (barbianj) has build some stands

If you'll notice, most store built stands for glass tanks are open in the middle.
I have built a stand for my 180, it has a few crossbraces acorss the top, and is otherwise open in the middle on top also.

 

I used 3/4", but it may be overkill.

 

So it sounds like the tank trim is already supported by 2x4,s. I was under the impression that the 2x4,s were not under the tank and the plywood was going to hold the weight of the tank.

 

Thanks for replys all, so should i leave the 1/4" plywood or remove it, for my progress so far see link below with pictures,

going to start staining it soon once trim is finished


Barbianj, can ou please take a look at this thread and tell me what you think, need to get it right first time, tank you so much

http://www.3reef.com/forums/i-made/...old-bigger-sump-help-153530.html#.U2-mU_RDsUM

 

I took a look and posted in that thread.

If the tank's perimeter is over the frame, ply or not, it's OK.

If the tanks perimeter is supported by the ply, which is then beyond the perimeter supported by the frame- change it, the perimeter has to be supported by the frame.
IMHO, you could leave the ply anyways, if the DT's perimeter is directly over the supprt frame.