Hard water is really not a problem. Use of rain water could be a problem,
since it has no KH and your KH is at what I would call a lower limit. If it
drops by 1/2, you could be in for a pH crash. If you have not been doing
partial water changes, removing water from the pond, rather than just
topping off, then evaporation of your mains water will increase the GH.
Check the mains water and see if there is a significant difference. If so,
it would indicate a significant water change is in order, if not, then don't
worry about it.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html

"billfish" wrote in message
...

My pond test strips I bought on Ebay finally arrived after waiting 19
days for Royal Snail Mail to deliver them, so I did a test. Most things
are OK, (NO3=10, NO2=1, a bit high, KH=6d, ph=between 7.6 and8) but the
GH is very high at 16d. The instructions with the test strips say to
do a part water change using rainwater. As it is not very rainy at the
moment, is there another, safe, way to lower the GH a bit?


--
billfish