Still experimenting.
Right now I soak in a bleach/dish soap solution for several hours. Rinse. Spray with pure ammonia (not the stuff with soap in it), cover and let it sit in the fumes for at least 30 minutes. Rinse. Then run it through the dishwasher to clean off all the chemicals. I use the high heat (140 degree) "sanitation" cycle.
Everything is washable: tub, water dish, hide box. Substrate is paper towels. I'm changing the water dishes every day (have plenty of extras). Water dishes are filled from a reverse osmosis filter.
BTW: The percentage of sodium hypochloride in bleach varies. Normal Chrlorox is 3.5%. Ultra is 6%. Other brands vary. I buy generic 5%--again, no soap, perfume or other garbage.
I've got Novalsan and ordered some Roccal-D. Like I said, still experimenting.