Can you not soak your oxygenator stones in a calcium remover/solvent?

http://www.ehow.com/how_2000311_remo...ower-head.html
http://www.nextag.com/calcium-lime-r...er/search-html

for example...

Watercress and mint are both pretty tolerant - they won't oxygenate the
water though so that is probably not what you are asking for.


"Davy" wrote in message
. 109.145...
I have several oxygenators in my limestone pebble lined
pond. Unfortunately, many of them become covered in
limescale; at best they look unattractive: at worst they
die.

Can anybody suggest plants that are likely to thrive?

Davy