Jacky,

The airstones do two things, one increase oxygen and two cause movement of
bottom water upward to mix the stagnant water on the bottom with the aerated
top water. Do you need one? Look at your fish first thing in the morning.
Are they gasping in the waterfall? Or are they swimming around normal. The
oxygen level of most ponds is lowest at daybreak, since the algae and other
submerged plants have not been creating oxygen through photosynthesis but
consuming oxygen. So if the fish are going to show signs, it is first thing
in the morning. No gasping, normal swimming, then you have plenty of oxygen
in the water, for now. As water heats up over the summer, or the water goes
green, you will find the oxygen level drops even more. If you find fish
gasping, give the pond a pint of hydrogen peroxide and go buy a pump.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"Jackytar" wrote in message
...
I just wanted to thank everybody for the good advice on my recent pond
crisis. We had a dead koi, at least one distressed koi and a faint sewer
smell to the water when we got in to do some maintenance. Folks here
recognized it as an oxygen deficiency with resulting anaerobic breakdown of
plant debris (which releases hydrogen sulfide gas... I'm learning!). Well,
my fish are looking much healthier now and my pond smells mountain lake
fresh. This was accomplished by a 50% water change w/dechlorinator, a
cleaning out of all visible debris... I did find a rather large, dead, lilly
root system under some planting medium in one corner of the pond... and by
correcting a significantly decreased water flow over my water falls caused
by a partially obstructed pump intake. I'm also treating the fish with
formalin (sp?) for good measure. The cause of the crisis was my ignorance...
no water changes in the 10 months since I purchased this home, failure to
recognize the clogged pump in a timely matter, and no knowledge of
oxygen-starved fish behavior.


I'm exploring the idea of adding an aerator, as was recommended by some
contributors here, but I get conflicting information. First of all, the pond
is 3 yrs old and the previous owner did not have a mechanical aerator. There
are two waterfalls that make some noise, and today I'm adding a water
spitter (which the previous owner did have). The pond seemed to be doing
just fine with proper maintenance and no mechanical aerator, at least until
this dunderhead took over. Secondly, the local pond retailer and "guru"
doesn't even sell aerators. He says there are very few if any ponds in this
area (south Louisiana) that has one. Thirdly, the pumps and airstones
designed for outdoor use I'm seeing for sale on the internet are designed
for *much* larger ponds (mine is approx 1000gal). So I'm wondering... is an
aerator more of a "boost" to a small pond than a necessity? To be honest I
would prefer not to have an aerator if it is one of those "might help, won't
hurt" deals. It just means more unnatural looking equipment and noise, not
to mention the expense.

Thanks,
Jacky