[Ross]

Originally Posted by R Srinivasan

It is a good idea to use fish tank as a terrarium. Your medium is good enough for growing orchids. Once you have planted and given a good spray of water mixed with a mild nutrient such as Schultz or Phostrogen thoroughly wetting the plant and the medium, you need not open the glass lid of the fisf tank. Try not to leave any gap while covering the top both to exclude insects and fungal spores. Terrarium are supposed to recycle their own trapped moisture to create an intimate micro-climate of their own for the plants. There will be little need to spray them thereafter.

I find a few things to be concerned about. First there is a big difference between Orchidarium and Terrarium. You are correct for the terrarium, but very few orchids will do well under moist stagnant air. One that will is Dyakia hendersonianium. Most need some air exchange and breezes to inhibit rot and mold. Algae is another thing to combat with orchids due to the high levels of nitrogen and light. An orchidarium usually enjoys some air exchange, constant air movement - often enough to blow the plants about, and high humidity (sometimes over 90%) I have no problem growing nearly any Angraecoid and also grow several Dendrobiums that need high light. I also tried a Tolumnia (the question above) which rotted. In answer to the Tolumnia, I would grow it bare root and out of the misting but exposed to the fan. I plan to try one again under these conditions. Tolumnias will grow and flower under t5 florescents just fine, but roots have to dry off at night.