Interesting, I looked though the ICP results, I've never run ICP on a sample from my tank. Everything looks pretty good except the trace elements, but I'm not sure I'd read too much into that as it's difficult to get meaningful numbers from tests when you get into those low ranges. Still, you at least know it's probably not TOO much of any particular trace element.
>I dont think you can supplement deficient trace elements with water changes. <
I disagree to some extent. Most salt mixes are made from fairly crude chemicals to save a buck. That means that with every gram of sodium chloride for instance, a bit of many other trace elements usually come along for the ride. If you had a tank with a lot of fast growing SPS (or other corals) I agree that supplementing trace elements just by water changes (particularly if you don't do them often) might not be enough.
After looking at this whole thread I'd still be inclined to say a fairly easy fix (that won't be a danger at all to your tank) would be to quickly get your alkalinity into a higher range. When I'm ever in a low alk situation I immediately do as follows. Yes, I know that the ocean is close to the same alk as your tank, but the the ocean is BIG and the alk/Ca/Mg and everything else doesn't change much. In a closed system such as we keep, I believe it is ALWAYS safer to keep alk well above NSW levels, particularly if your tank runs on the lower end for pH. In the short run you could instantly correct your (potential) problem with a teaspoon of baking soda per 20 gallons of water (dissolve in a bit of fresh water first). Check alk a day later and if it's not at least at 10 dkH (3.57 meq/l) add the baking soda again.
Also, I don't know what your VHO bulbs are really putting out. I'd be inclined to see the MH on for at least 8-10 hours/day. Particularly for corals at the bottom of the tank. Do you see a difference in health of corals at the top vs bottom of the tank?