I use 2% Chlorhexidine diluted with water in a spray bottle for spot cleaning. In the tubs I also use non-scented baby wipes.
I also use the diluted chlorhexidine for full cleaning and cleaning hides and water dishes.
I dilute Chlorhexidine as well...I make 1.5 gallons total, and soak all the furniture in there for 2 minutes. Then I start to fill a spray bottle with the dilute solution, and I spray the tank. I repeat over and over until I have sprayed about a gallon of the solution.
Contact time is important...so I spray the walls, and as it drips down, it pretty much gets everything. After about 6 refills on teh spray bottle, I am done...I dump it, rinse it...and then dry it.
There is no danger in leaving any of the residue...which is why I use it.