that may work, but if it looks pretty bad i'll bet not. go to your local wal mart or equivelent. buy some WORKS toilet bowl cleaner. one bottle should do it. if not, they only cost about a dollar. youll need to plug the petcock hole. i usually throw a few screws in the tank first, shake it around really well, then with a long magnetic screwdriver, take them back out. now for the fun stuff. pour in a bottle of the works, then fill the rest with water. let it set. i have let them set over night with no ill effects. the next day, pour the mixture out (according to EPA regulations
) then rinse the heck out of it with water, i have done it about ten times. i would recommend sealing the tank with por 15 expensive, but worth it.
disclaimer, the works is ACID so be careful. by doing this, you take full responsibility of your actions. WEAR RUBBER GLOVES!!!!
now back to our regularly scheduled programing