You could always take tank to a welding shop that know how to test the type of metal and proper procedure to weld aluminum.
I took mine to a local welder that said he could do it, but he ruined the tank. Three holes I could stick my finger in. After that I found a qualified shop, would have been about $50, but they didn't think a patch over the mess that big would last. Bought a new tank, all said and done for $430.
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