If you look at the previous pictures you can tell that for the bottome and tops except for the very type is all malomine, and it is all surrounded by oak plywood. Yes I found the ventilation to be necessary in the middle so the above tanks temperature is not affected by the heat generated on the top of the bottom tank, and it does affect it without the cooling system

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and you can also tell in the previous pictures that I use plywood for support.

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