Keep in mind there is no reason or need to "sterilize" your tanks or tubs every time you wash them unless you are dealing with a sick animal or a quarantined animal. If you try to sterilize every time you wash, you are doing more harm than good.
Why does it do more harm than good to sterilize?
I clean all of my occupied tubs in my racks with chlorhexidine once a week and every time they pee or poo. Water crocks go through the dishwasher once a week also.