I've drained my old pond in order to clear it of pollution and duckweed. Can I use weedkiller to eradicate it?
Or will this harm the fish when I refill it? Obviously I would rinse it off afterwards, so there could only be trace amounts of the stuff left, but is it safe to use at all? The duckweed can grow to cover the entire pond's surface from just a few seeds, so it's VITAL that I completely destroy it now while the pond is empty of water and fish.
Alternatively, as the weed seems to be dying off and turning brown now that the pond is empty, will that prevent any chances of it returning?
Answer:
If your pond is concrete, liner, anything but a natural bottom, you could use chlorine to clean it. That will kill the duckweed. Then you could add extra dechlor when you refill.
