Hi Debbie, Interesting post. Reading about the folks 'down under'... they often add salt to their system. Every thing I've read, they say NOT to use salt with Iodine..'?' I belive they said it's not good for the fish (?)....then again, maybe it's the fish they raise.
I don't use the refined salts anymore either. I do use a salt called 'real salt'. (for me , not the fish) It has lots of trace minnerals and a little iodine. Lol...it looks like dirty salt. It doesn't taste like the 'white stuff' either...it's a milder taste.
I'm from the north east originally...for some reason, that area has a high issue with thyroid problems. I remeber my grandfather having a large growth on the side of his neck
Iodine in AP
Let me fist say that I believe that there are two types of recirculatory systems (in a controlled environment). One is where everything is as natural as possible and the other is a compromise on sustainability for the sake of production. Although we aspire to the first, it is common for most to be more practical as livelihoods depend on success.
My background in hydroponics gave me confidence to use salts and by study, trial and error, was able to formulate some rather impressive results for specific crops. I learned that plants do not need iodine to live, however we humans and other animals do need it for our good health and the only way for us to obtain it (iodine) is through vegetation that is grown in media containing this element. In this case, iodine came from Potassium iodide or Cobalt iodide in my trace mineral mix. As much as I love to be sustainable, I still balance my systems with salts to this day.
In my larger experimental ponds (1/6th acre +) I use a UV sterilization to terminate and control the microbial activity so the good bugs have a fresh start. Remember, the point in the sustainable experiment is to recirculate water, not nutrient. All nutrients should be used up so the first tier of fish has rainwater/ spring-like, clean water.
In the second type of system where I only use tanks for grow-out, I use common iodine crystals to make a spray to disinfect my smaller systems (up to 2000 gal) after each harvest. I do this because in a system like this, the new stock might not have the immunity built up like the previous stock had. Nothing goes to waste however, as this “polluted” water is stored in a large, aerated cistern which is used for top watering the raised beds as well as to dilute ground up solids in the bio reactor in my three part compost operation.
This is one of the things I intend to study and balance to become a sustainable part of our AP systems. I am working with a feed producer which adds iodine to my mixture that, yes, does contain some seaweed.
Here is a site I use to use. Maybe it might help. :http://www.ublcorp.com/files/AquaCulture.pdf