Hey all!
I have a small collection of about 20 paphs & phrags (mostly seedlings) and 15 or so other genera. I live in a northern climate and grow in an old leaky sunroom. The slippers mainly grow on the top tier of my steel wire shelving unit, lit by a 4 bulb T5HO fixture. The middle tier is lit by natural light only. To try and keep my plants warmer & more humid in winter, I bought a clear vinyl cover for it. It set me back quite a bit (

) but it is working at both jobs I had pictured for it.
Here's the problem: It seems that since I have changed from an open air shelf, to enclosed, many of my slippers are experiencing leaf splitting (or at least the onset of splitting). Humidity has increased from 50% average to 70% average during the day, 50% at night. A muffin fan circulates air inside the enclosure, with slight movement of the leaves of larger plants. Temperatures are 72-75 daily, 58-64 evening.
I water all plants from below using stored rainwater, and soak the media (bark, perlite, sphag chunk mix) every 3 days (nearly dry throughout). I rarely fertilize in winter, maybe 1-2 times per month.
What could I change in my culture practices to avoid this leaf splitting? Plant growth is great, otherwise! Thanks for your help!