I'm trying a new gadget called H2Out. It installs on your tank vent line to absorb humidity from the outside. When the pellets turn pink it says to remove it, wash the beads, let them dry and reinsert them back in the container; ready to go again. If it works it will be well worth the money.
The promise is no water in tank and we all know if you get water you risk a build up of crud and possible rust.
H2OUT Company Website - http://www.h2out.com/BY The Way.... for what it's worth.. my 1982 model 37C has the original sticker on the tank. It was made by Florida Tanks, aluminum and has a capacity of 53 gallons. Not sure what the rest of you have..