Thanks for the question, Andrea. You could add to either or both. If me, I like to add a full can of Sea Foam to a tank when low to increase the cleaning concentration. If you have to choose one or the other, add the tank with less fuel or wait until one of the tanks is low before adding. Hope this helps!
Thanks for the question, Andrea. You could add to either or both. If me, I like to add a full can of Sea Foam to a tank when low to increase the cleaning concentration. If you have to choose one or the other, add the tank with less fuel or wait until one of the tanks is low before adding. Hope this helps!