Questions I get:
What is horticultural sand?? Sand box sand? Vermiculite?
Horticultural sand is just sand that has been rinsed and is very clean. You
get it at the nursery or garden center. It's a bit pricey for sand, but is
not highly alkaline, and is better and easier in the long run. Save it year
to year, rinsing it before each use.
It is great to pot plants in because it contains no organic matter to discolor your pond water. It's also great for overwintering plants.