If you are going to use air stones, then you will also need to have a pump
to run the air stones. The small aquarium air pumps with the appropriate
aquarium air stone is sufficient. If you were able to smell anaerobic
odors, then I would suspect that you have a layer of debris on the bottom
that is several inches thick. If this is the case, you will need to remove
that debris with a vacuum or fine net. A larger pump or an air stone won't
do much to help with the problems associated with thick layers of debris.
Before stirring up the layer of debris and releasing the hydrogen sulfide
gas, which is very toxic to the fish, you need to add some potassium
permanganate to the pond to neutralize the H2S.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"Fred" wrote in message
...
My little 400gal pond has done wonderfully all summer long - crystal clear
water (after the spring bloom), lilies going crazy, fish thriving,
including
a host of new babies. However, I was thinning the hyacinth this week and
in
removing several plants noticed a subtle yet distinct odor that suggests
anaerobic activity. My little pump just causes a trickle of a waterfall,
so
I don't think I'm getting the oxygenation that I should have. So, here's
my
question:

I'm assuming air stones are the answer, as well as a larger pump. How and
what kind of air stones are to be used? Am I going to have to invest in
some kind of air pump as well?

TIA,

Fred
Oceanside CA