Mas. rolfeana culture questions

[Johndeaux22]

Every few years I tell myself "get some Masdevallia, you can get them to grow"....I've now done that again. I recently acquired a couple of hybrids that seem to be doing fine - new growths on both since arrival in December - along with a Mas. rolfeana that is aborting leaves like it's going out of style, and no signs of disease. Along with the other's it's in fine fir bark, that seems to be in good condition (came from Hausermann's, I think they use Rexius?) They're all towards the bottom of my grow tent with what I would describe as Phal. light, humidity averages around 80%, low temp is 59-60* F, highs are around 65* F. Water is RO, that usually reads less than 15ppm, but I have been watering with the rest of my collection with a dilute fert. solution (25PPM N, Ray's K-lite). Watering frequency is about every other day, never allowed to dry completely, but also not soaking wet.

My theory is that the M. rolfeana is exceedingly sensitive to water quality, and that the constant fertilizer regimen may not be to it's liking, so I've flushed the pot with clear RO water twice, an hour apart, and have set up to water it separately with clear RO only, with dilute fertilizer maybe once a month. Any other suggestions would be greatly appreciated.

I am also in the process of gathering materials to set up a large (55 gallon) aquarium/terrarium setup for pleurothallids that I plan on running intermediate to cool . My most recent Masdevallia purchase was with this in mind.