Cant grow Chysis?

[orchidfriend]

Hello all,
I have been growing orchids for a couple of years now and have had great success with Den, Phal, Paph, etc... but I seem totally incapable of growing Chysis. Twice before I have had well established plants that were happy and healthy until, seemingly for no reason, there leaves turn yellow and die. Now I have two more Chysis that are starting to yellow. I have also had similar problems with Gongora... I have looked at a couple of culture sheets online ut can not seem to find any reason why I should be having so much trouble. Can anybody help? I love the foliage on these plants and would love to be able to keep some alive.

I grow under Agro Sun Florescents and fertilize weakly weekly with MSU.
My only thought is that maybe I am giving them too much light????????????????
Please help

[LouisW]

I dont have any familiarity with this genus but from what i have just read over the internet is that some of the plants are semi deciduous and will loose their leaves. Could this be it?

[kmarch]

Yes Chysis, especially the somewhat popular Chysis bractescens, are deciduious and loose their leaves after a year or 2.