Great understory plantings could be philodendron and cool tolerant tree ferns.
Tree ferns are one of my favorite plants.
I have no idea of your planting space?
R/o watering should be out of the question for a ph issue in most applications unless your growing organic weed.
However there are solutions in the 500-600 dollar US range which will help.
Do an internet search (dosatron ph balance)
Tap/city water in most instances will absolutely work.
Cincinnati water is some of the best in the country......but it has Flouride.
My plants teeth shine!!!!
