My tank is these exact dimension. Mine is 1/2 inch but I wish it was 3/4 or 1". Mine is super stable and fine but the front does have a bit of bowing to it. 3/4 would be great and if I was building one that is what I would use. But one inch would be super super strong overkill in my opinion. Thicker than that you need to go for three feet tall 
If I got one inch thick I would be going for 36inches tall.

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If I got one inch thick I would be going for 36inches tall.

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