when doing a "total cleanout", i would use only bleach and water. It is safe if used right, cheap and easy to obtain, and is more effective in killing germs, bacteria, mold, etc than anything else available. There is no problem with using bleach. Do not spray your frogs with it or put your frogs in a tank that has bleach in it. That is common sense. It is not for just getting rid of parasites for QT, the frog can also get bacterial infections from inproper cleaning/sterilization of a tank. So whether or not my frogs have or do not have hookworms, the cleaning process would be the same for me.