Kettish -

T8 are good for AVs and other gesneriads - AV-s 10-12 inches from the top of the plants to tubes, 12 hours a day. I think all medium light house plants you can fit under - will grow OK.

I grow Paphs and Phals under 4 T8s.

irina

Here is a link that might be useful: Rachel's Reflections

I have kept AVs under T12 fluorescents before, and it's commonly done. For T12s keep the lights 12" above the foliage for standards, and about 8" above for minis. I believe T8s are a somewhat higher output so these distances might need to be a little greater. Even with T12s there is a little trial and error. If the leaves are drooping down move the light further away, if they reach upward move the light closer. AVs also need at least 8 hours of darkness in order to bloom, so make sure to turn the light off each night, or better yet, put them on a timer.

Thank you both! I appreciate the information. Irina, I'm desperately in love with catts, unfortunately, as it's going to be expensive to get them the light they need. I only have one for now under a T5 with my other orchids, if the others start to have problems I'll switch them down to the T8.

Well, here's hoping! Off to put my lights up (and on a timer, as snappyguy suggested).