Sorry, I meant that last line to be a new paragraph, and I couldn't
remember what the Barley was for. I wouldn't use it till you actually
had an algae problem, because algae IS part of the nitrogen cycle.
I guess you could also use rocks from an established healthy pond to
help set up the new pond. You do not want too many rocks in your pond
though, because it will be harder to clean.
You normally use rocks to hide the edge of your pond liner or
container. You can also use rocks to build a wall on the uphill side of
a pond, but you'd probably need to put liner behind the rocks, and
mortar them together (big rocks with little rocks to fill the gaps.)
Randy R