Terrarium advice needed!

[greenbean]

Hi everybody!

I've tried growing in a terrarium (without orchids) twice with the same result: fuzzy mold and big yellow mushrooms! ) The plants did fine, but I couldn't stand those fluorescent yellow mushrooms! The tank I have is 20 inches long by 10 inches deep by 12 inches tall, has a fluorescent tube that delivers, if I remember correctly, about 2000 fc near the top of the tank. I've never measured the humidity, but I had occasional problems with too much condensation on the sides, so it's high.

I would like to try a third time, but this time without planting anything directly in the terrarium. This time I want to put gravel in the bottom with potted and/or mounted orchids and possibly put moss or something around the pots to disguise them.

Given the size of the tank, minis are a must and I'd like to include jewel orchids too. So my questions are:

1) Is this tank even big enough to suitably grow a few minis, or should I look for a bigger tank, and if I need a bigger tank, where can I get one for reeeaaallllly cheap?

2) Are there any orchids I can grow in the terrarium that wouldn't require a fan, or would I have to try to find a fan for it?

3) I think the mushrooms came from not sterilizing the soil, and there won't be any soil this time, but what should I do to help avoid disease?

4) Does anyone have any advice on things I've overlooked or helpful suggestions?

Thanks for your help!