gas tank rust removal

Been looking for an elusive thread for 2 hours.
Can someone refresh my memory about a Home Depot product for flushing out a rusty tank?
Any sealant suggestions other than 'Kreem'??

Hydrochloric acid based toilet bowl cleaner will get rid of rust. A phosphoric acid that is used in tile work will too. To stop flash rust, Jasco Metal Prep which is a milder phosphoric acid solution with other additives do a nice job. I don't know about sealing- never needed to.

Elusive thread maybe:
http://www.motoredbikes.com/showthread.php?t=16733

I purchased a product called Caswell Gas tank Sealer. It is a 2 part product that coats the inside of the tank. To prep the tank for use it says to put a handful of deck screws in the tank with acetone and shake it around a lot. The good thing about this stuff is it holds better to a little rust. Not loose rust but surface rust. I'm using it on a 1946 Whizzer tank.

Jim