I would just love a large pond full of bullrushes, Mswoody. I don't know that you can kill them without doing a lot of damage to the rest of the ponds ecosystem. If they are too dense for you then I would suggest that you would have to physically haul them out, by hand or with a JCB depending on just how big your pond is.

thanks for your advise seem to be getting the same answer all round, looks like a lot of work for hte hubby in the winter months...

By Bulrush I presume you mean "Reedmace" or alternatively "Cattails" (genus Typha) Mswoody?

The true "Bulrush" is a type of sedge (Scirpus).

if its a cement pool get in there with a bread knife and cut it into managable lenghts . infact you could do it with a liner if you use one of them bread knives with the curved blunt end . take them out and let them dry to deat and fill your pond up or clean it out and start again . youl have to get the speedos out lol .