Thanks for the comments Crease and Audi! The green stuff is caulerpa macro-algae. I like how it looks in the tank and it helps to control phosphates (mine stay at 0 or VFT).
I typically dose Kent Tech M Magnesium, Kent Purple Up, and Seachem Iodide halfway between weekly water changes. I think I am going to change this up though. My Mg has been staying constant, but my Ca has been running a little high and my Alk a little low, so will probably be switching to a 2-part Ca/Alk in conjunction with the Mg/Iodide.
Other than that, I do weekly 4-5gal water changes along with a deep/aggressive vacuuming of the sand and a thorough glass scrubbing. Rocks/corals are cleaned with a turkey baster 2 times a week. I use a cut up filter sock in top tray of media basket which is changed out daily. I also alternate adding phyto/zoo plankton a couple times a week.
As far as dosing, just make sure you are testing for what you are adding, unless you have a heavy coral load it's probably not going to do anything for you (and isn't needed). Weekly water changes with quality salt mix are likely enough for the majority of situations. I never noticed levels moving before adding 6-pieces of SPS and a clam.