The Beave suggested I use an Open grate style shelf. I found a 13 Gauge, 3/4" one at Tractor Supply. And a cheaper one at HD. The one at HD is 1/2" spacing. And it states .125" which tells me 1/8". These are 12" x 24" pieces. Which would work for the two upper shelves. Not sure if I want to Trust that for under the weight of the Tank. I am thinking about the two at HD. Would get me started. The bottom one would be welded on last.