I've had my N. eustachya for a while now and I'm pleased with the way it's growing but the top surfaces of the leaves have a very thick whitish waxy coating or something that almost resembles calcium or sodium stains. I only use R/O and distilled water combined with occasional light doses of fertilizer.
I tried the trick of washing the leaves with a slice of lemon but all I got was a lemon smelling terrarium for a while the waxy coating remained on the leaves.
What is this coating? Do all eustachya make this?
None of my other plants make any coatings on their leaves like this.