I use the flat kinda cardboard looking ones, my supply guy said they are better then the rigid plastic ones.
When installing the tank I noticed moisture in the line that comes directly out of the regulator so I checked everything out and it seems that the back pressure when turning off was drawing water from the bubble counter into the needle valve, ugh. Used to have a check valve there but forgot to add it back in when I put the new bubble counter in. So I am assuming that if the needle valve got water in it that it might clog enough to make a leak spring up somewhere (like the hose connection right before it) and that is where all my gas went?
I installed the new tank and did a really through leak check and everything is good.