Just FYI if you want a 1 BBL mash tun you aren't going to get there with 20gal. 40-50 gallons will be appropriate for 1BBL batches depending on what max gravity you'd like to achieve.
Thanks for that, but I meant 20 gallon - 1bbl just want to get my batch size up preferably to 1bbl but if someone wanted to get rid of a 20 or 30 gallon it would be a stepping stone as there's no rush.