"DD DDD" wrote in message
...
I have a 300 gallon pond. The filter and pump is 1800gph which is way
overkill. My problem is Sometimes I want it quiet by the pond so I can
just look at my creatures without them flowing around from the strong
current the pump makes. I can slow down the filter a little but it says
no more than 2/3 . And if I shut it off to long I kill the bio filter
bacteria. I guess my problem is I just need plenty of oxygen so my fish
are happy. When I shut off the pump for a hour or so they just get lazy
and seem to need oxygen. I was told a airpump puts no air at all in the
pond , that it just makes rolling water that adds oxygen. Is this true?
The airpump must put some oxygen in. I have 3 small turtles in the pond
also and they hate the rapid moving water. I have the 1 1/2 inch outlet
hose on a rock that makes it like a waterfall and the fish are lively
and love it. So cant I just add a few air stones or air bubbler when the
pump is off for about 1-2 hours? I lost 1 turtle already because the
flow is to much. I cant put a fountain in either. Help

Your pump is better suited for a much larger pond, or for a higher
waterfall. In such a small pond, you can add an airpump, or a much smaller
pump. Something in the range of a 200 gph would probably suit your needs,
smaller then that, and the pumps are better suited for use indoor water
fountains. A smaller pump would also reduce your energy consumption.

A smaller pump will also draw less electricity.

You were told correctly, the oxygen to water exchange happens on the water's
surface. The surface area of an air bubble is so insignificant that it makes
almost no difference. If you had an airpump that always had 1000 air bubbles
of 1/32th of an inch in diameter in the water, it would only produce about
12 square inches of additional surface area.
0.03125 * 0.03125 * 4 * 3.14156 * 1000 = 12.27171875

The air pump on the other hand causes the water to circulate, bringing water
from the bottom of the pond to the surface where oxygen can dissolve into
the water.

-S