I think magnesium is just so soluble, it washes away or leaches out and the plants can't store it. It really seems like you can't give orchids too much. Other plants like it, too but there must be some in the soil, or at least it stays in the soil a little longer than on orchids and other epiphytes.
You must have arrived just after the monsoons up there finished this summer. Pretty sure April through July were record-breaking for rain in Tampa. So there is relief in store.
I love the micro-irrigation mist system. It's almost invisible, as well as just about infinitely expandable and flexible as your collection changes and grows.
