Pine Sol has been used. Dilute by half with some very hot water. Get the tank warmed in the sun and pour in the hot solution. After it cools, pour it out and heat it up again and reuse. Never tried it myself. Just read about it. Adding the chain or gravel should help too. I think getting a HOT solvent inside will help a lot to dissolve it.
Last edited by Lugnutz; 10/24/2015 3:59 PM.
