You can raise the peppermints in a standard 10 gallon tank, with just a heater and air bubbles in the corner. Feed them baby brine shrimp and siphon out any detritus that builds up. After a couple weeks, you can even feed them frozen foods, and they'll pick it up off the bottom and carry it around with them. I've never had iodine issues, as it's already in our salt mix. Highly unlikely your water is deficient in it.
Biggest problems you'll encounter is with the late stage larvae breaking off arms. Bubbles are like wrecking balls to those guys. If an arm breaks off, it takes 3 molts to grow back, which is 12 days or so. They will only settle if they have all their arms, so it can be frustrating when you check and find your biggest larvae missing a leg. lol
I know it can be done in a small tank with air line and bubbles with constant water changes ect ect, but the system I'm running is very different and I'm trying to get away from the hours and hours of maintaince every day as I'm trying a new style of system when I can start doing these on a large scale.
So far to date, I am not seeing anything that points in the direction of the system it's self being the problem as in the first few batches, I did tests every day for about 6weeks and all readings and temps ect ect came back with acceptable results
Thou I will try and add some crushed up flake to the mix and see how it goes