I tend to agree with the Gentleman from Hawaii.
I fall back on, "When in doubt, I flush it out". Water Changes are our friend. Better lighter concentrations of nutrients for weaken plants than an overload, until they stabilize.
Part of the problem with crypt collectoris is that not all in your collection have the same requirements. While they all might do O.K. in the mid range, I think your seeing that when you find the range that some thrive in i.e. your Borneo crypts the others Sir Lankan, Phillipino etc start to fail.
Collectoris is a cruel master