I bought 4 of them and also have a pair of some cheaper harbor freight dual suction cups also. Thinking I should be good… I hopeMy buddy owns a granite instillation company and they use suction cups like the first ones posted to carry and move large pieces of granite around. I have no doubt they would work on your tank. I would think you could go with 2, one on each end but 4, one on each corner would probably be easier.
corey