How much iodine should a 15g nano moderately/lightly populated with soft corals and shrooms need? I plan on using Lugol's. I don't intend on testing for it unless I have too.
That is a question that I have intertained. I don't use any in my 125 and my softies mushrooms, fish are all fine! If I myself was going to add Iodine I think I wsould test for it first? But than I'm still a Newb!
If you are feeding regularly and doing water changes, you probably will never need to add iodine. According to Borneman's book, there is no evidence that most corals need it (although some report good results for Xenia), and some corals seem to react badly to iodine additions. Unless you have large growths of macroalgae, it is probably not being depleted significantly. Furthermore, most test kits are not very accurate, so it's hard to judge how much to dose.
definate no on iodine.. some shrimp use it to molt and grow faster.. but I have had shrimp and personaly never added iodine and witnessed crabs and shrimp molting just fine.... I have heard of some corals being poisoned form iodine... I would stay away from it... Just my opinion though