Question about Iron

[Parnold]

My reef tank has been set up for over a year. The macro algae in the refugium, hasn't grown at all. I have a 15watt lifeglo fluorescent light that stays on for 12 hours. Have tried a few different algaes but chaeto is what I have had for a long time. My Nitrates are high but everything else seems fine. I have read that you should have some chelated iron in planted fresh water systems, so I tested my water and found the reading to be zero.
Could this be the problem? If so can you add chelated iron to a reef tank?

Thanks