Are you using something to reduce the water's surface tension so it can cover the leaves? Without that, you're just adding to the RH of the tent.. and if that's what you want to do, that works great. From what I have read, unless you are addressing specific deficiencies, using CaMg supplements as a foliar feed (instead of or in addition to adding it to the feed solution) is a nice way to quickly address Mg deficiencies. There are many more here who know much more than I do on the subject.