Gardens River boulders
AM told that river boulders are bad for a pond. Why is this?
is not so much that they are bad, it's just that river stones tend
to make the water very alkaline and this has consequences. If you
do use them, make sure you monitor and adjust the water pH regularly,
especially for the first year.
I recommend Pond Balance
for this purpose. Make sure you follow the instructions, as sudden
large changes in pH are harmful to fish.
The worst consequence
of a high pH is that it encourages blanket weed, a particularly
nasty and difficult to control fibrous algae.
On a personal note, I
do not like river stones in ponds as I have had to clean out many
ponds with them. It is a very time consuming and tedious task I
Gardener, Issue 96, 2002, Page 22
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.