orchidarium building

If the tank is humidified with an evaporative cooler or humidifier as you mentioned, you will like only need to water every few days so you could get away with just a hand sprayer. Thats what I do in my tank.

 

I'm currently growing in a 36x18x36 (It's an ExoTerra base with a 40 breeder aquarium flipped upside down for the top.). I light it via a 4' 2 bulb T5HO and two LED bars across the front. Light to the bottom is fine...You just can't grow Cattleya and such. Since the top is an aquarium, it is totally sealed besides the vent at the base. I run a fan inside and keep the ceiling fan in the room running for air circulation. I water ~3 times a week and humidity is well-maintained and barely reach dryness before its time to water again. This is my 6th growing case over the years, and this set up is by far my most successful.

 

As for your smaller tank, it sounds like you have a lot more air movement than you need. Does your fan run constantly and do you have speed controller for it? I would recommend putting it on a timer or adding a speed controller and turning down the speed or both. I run my fan on a 1/2 hour on, hour off cycle with it at a fairly low speed and it works fine for me.

 

You can buy fan speed controllers for a few bucks on computer parts sites. You just wire them in between the power source and the fan. The reason you have having to water so much is that you don't have a door on it so it's basically at the ambient room humidity. The point of a tank is to hold in humidity, almost like a greenhouse in miniature. I would put the door back on and just cut back on the watering to control fungus rather than killing the humidity.