Question
I am planning to convert several of my aquariums into orchid cases.  I plan to build a 'hood' which will contain a misting system (drawing water from a reservoir below), lights and fans to provide adequate air movement.  I've also been researching humidity trays and was wondering if creating a tray in the bottom and providing slight heat to foster evaporation would be better than the misting system.  I'm just afraid that applying moisture from overhead will cause crown rot on my phaleanopsis plants.  Also I already have florescent light fixtures, would these work for their growing needs (with different bulbs)?  Or do I need to devise a lighting system with blue and orange/red spectrums?  What are your thoughts?  I am stumped with all of these variables and don't want to have to re-build the system.  Thanks for your help.

Answer
One caution I have for you is not to go "whole hog" and do a massive conversion to terrariums.  I recommend that you start with one.  You are right that there are many factors to balance off and it is often difficult to obtain the right balance of humidity, air movement, temperature, and light.  One problem you may encounter with growing phalaenopsis in terrariums is that, when flowering, the flower spike may grow to a length taller than your enclosure is tall, requiring that it be grown outside the tank at that time.

You are right about crown rot in an enclosed system with an overhead watering system.  By using it early in the day, then keeping the cover off and running your fan(s), you may be able to avoid crown rot by evaporating the moisture left in the crown.  Another option is to use a swamping system which keeps water out of the crown.  The latter uses a small pump to pump water into the tank to a predetermined level and another pump to pump it out after a set time has elapsed.  You may need to run that only once per week.  The tank walls will help to maintain high humidity in the growing area, so your biggest problem may be a potting mix that retains too much moisturethe plants inducing root rot. You may need a potting mix that is quite course allowing for more air movement in the mix.  You will need to experiment with all of this until you get the conditions right.  If your aquariums have different volumes, the parameters for one tank won't necessarily work for another.

I have found that four 4 foot florescent lights work just fine for phalaenopsis.  You could use 4 cool white or a combinastion of 2 cool whites and 2 warm whites.

Remember that each enclosed system is unique and you will need to keep records to know when one of your parameters needs adjustment.  Once you get it right, you can automate the entire sytem.