Best available alternative to PrimeAgra leca

[Ray]

I may be a bit biased, since I originated semi-hydro culture for orchids, but...orchids in nature typically grow in some sort of solid medium, not water.

The guy who originated water culture found that the water fouls after a short while, and that many orchids required that the temperature be kept elevated for best growth. At least with S/H culture, the water is refreshed at every watering, if you do it right.