I have quite a few orchids growing in my various tanks, and i have planted them at all times of the year. I have had very good luck with paphs, smaller cattleyas (plant these near the top of the tank closer to the light, and only if you have a bright light) oncidiums, and some of the smaller dendrobiums. I have not had very much success with phals in my tanks. The only one i have managed to keep alive is one p. amabilis, and it isn't that great looking.