buildup or moss/mildew problem

[Ray]

Considering that the buildup is on the plant as well as the medium, it is definitely a mineral buildup issue, so no chemical treatment will fix it.

Considering how dry that pot looks, I think you're not watering often enough and/or are growing in a very dry environment.

Vicki, if you have switched to watering with distilled water, you cannot continue to use Dyna-Gr "Grow" formula without adjusting the pH of the solution up a bit. D-G in pure water will give you a pH of about 3- to 4. What type of filtration does your household water have?

As a point of reference, for folks that don't clean the LECA well enough to start, the leachate deposits are tiny needle-like crystals that look fuzzy, as opposed to the "cement" appearance of limestone from the water supply.