Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
You can probably keep it under control, but not kill it by any of several means:
First of all, is it really Java Moss, not one of the stringy algae?
Remove existing plants and drain the pond. When the JM has dried, rake it out.
Remove it in as large a mass as you can and sell it (RAOK, send it out if someone (Jake) will just cover the postage, but in warm weather send it Next Day, not slower)
Remove it in as large a mass as you can and take it to the local fish stores (I know there are many in Sacramento) for a little credit.
Remove the good plants and overdose with salt. (It takes quite a bit to kill JM). You will then have to drain the pond, scrape out most of the moss, rinse the pond pretty well, then refill. The trace of salt remaining is not a problem for the plants.