leaves that don't open

[Stitzelweller]

Originally Posted by monna lisa

You're right kavanaru, leaves are smaller than normal, but I found that the issue was the too long lasting photoperiod (when I had the CFL lamp, I set the photoperiod on 16 hours of light, and when I changed lights to MH I left the same amount of light hours...so new leaves grew smaller. Now that I've changed to 12 hours of light things are getting better)
I'm using a fertilizer for R. O. water, very similar to the MSU one (Akerne's rain mix) and the water solution pH is around 6. The strength at which I use it is around 350 microsiemens for botanical orchids and 400 for hybrids. Vanda gets a 800 microsiemens solution.

monna lisa, will you please translate "microsiemens" into a meaningful measurement of light intensity? I'm old-fashioned; I understand foot-candles and lux.

thanks