Nursie, I dose 1 drop per 5 gallons after water changes as mentioned above, the Shrimp factory reccomends 1/4 teaspoon per 25 Gallons (I believe) most folks don't dose iodine as often or as much as I do for shrimp. A little goes a long way. If you aren't having any problems, I wouldn't worry about it. some folks get enough through their drinking water to suffice, and there is some argument about it's need in the first place. I can say I have seen better results with iodine than without. but the whys and the hows are still a mystery.
Dave
Dave
