Did you? Lol.. Comical.. I wondered how everything went for you..
Lol, i just got tired of waiting for anything to grow. I had that light on that fuge for over 3 months and nothing... Lol, then, i saw a couple tufts of hair algea. Yes, control nutrient with gfo and other means, but there are more ways to skin a cat. The funny thing is when i went in the store to buy the light, the guys said I'm like the third person they have seen try this. I told them that this wasn't the first time i did this (new store i am going to) and the results.
They then laughed with me, as i told them, both how much the fuge lights run, and how people struggle to get growth from cheato, which in essence is just an underwater plant. We talked for maybe 30 minutes about it, and about led light, etc . Also how it relates to hydroponics and aquaponics, etc.. It's always insightful talking and catching up with newer tech in above water plants..
But I'd love to see some pictures of your setup, as what your proposing for yours is my dream setup with a remote fuge area. That, and growth pictures. Me though, I would try without the iron first. If nothing else, as a control and without adding an additional element to the water. After all, our goal is to "extract" and not add.
The planted tanks, yes, but for what we are doing, the potential synergy of tech from aquaculture and agriculture is tremendous. If i had your setup, i would do mangroves as the ones i had grew insanely fast (in two months i got like 6" vertical growth and tons of leaves, then below water, root structure was insanely trenched in the substrate:searching for nutrient and they looked great!). And pod growth was insane!
The main limiting factor in growth of most plants is not nutrient, as shown by hydro growth, but light! For light loving plants that is. And then, we ask know that we can never supply as much light as the sun can. But you can accelerate things massively! I really don't think most understand how insanely we can enhance things.. We really aren't throwing enough light at our fuges to really do much of anything. That's why there are the typical limits to refugiums: nutrient extraction, slow growth, needing big fuges to really do anything, and most importantly penetration of light throughout a certain depth..
And my levels dropped massively once the stuff started growing. It also was like clockwork after i harvested that it would go up a tiny bit and then pull massively once the plants healed and started accelerated growth again.. It really is fun to watch, a person just had to try it and watch the results..
Just talking out loud. Lol, like we talked, I have always loved plants and animal life. Anything to benefit or forward the advancement of both, I'm game..