Going off of Rich's suggestion, I do know of a homebrew supply shop that carries 14 gallon barrels that are intended for meat packing (clean and unused). Food grade plastic, snap on lid, locking ring for the lid, and stainless handles. He has a bunch of fittings and tubing too, so he can help you modify the barrel as you see fit.
He also carries different mineral supplements for adjusting water profiles to match different regions for specific beer styles. Could be handy to adjust GH/KH. I'm going to pick up some of these once I get my tanks situated and start getting serious with shrimp.
The shop is just over the border in RI. 403 Park Ave in Woonsocket, RI. Check here for the hours http://blackstonevalleybrewing.com/