A 2/10amp charger even when set to 2 amps when shorted out (like too much salt or a really dead battery) will go to max and even kick out the thermal interrupter.
I've read on the net that even if you don't put your feet in there it will still produce the 'gunk' in the water, have you experimented with this?
I to was thinking of trying this regardless of the gunk test just because people report good results which might even be from the electro-stimulation?