I spray my Tillandsia usneoides once a day with rain water. I hang it at my kitchen window. Yesterday I found that 30% of it are brown. What happen to it? It's over or under watered? Thanks in advance.
I live on the east coast of Aust two streets back from the ocean and I realise my growing conditions are probably much different to yours, but from what you say I think you may be overwatering your usneoides. I have it growing all throughout my shade house and in the trees in my yard and it only ever gets rain water which is not that often and it just grows and grows.
I don't know about growing it inside but there are many others here on the forum with much more experience and knowledge than I and they will help you.
I was told by an old nurseryman many years ago that more plants are killed by over-watering rather than under-watering and if in doubt whether to water or not, don't! Put it off for a day or so. Hope this is of help, all the best - Nev