On Wed, 19 May, Sir Douglas Cook wrote:

"Chuck Gadd" wrote in message
news

Completely false at levels encountered in our aquariums. CO2 levels
elevated to the levels used for planted aquaria (40ppm max) will not
prevent any absorption of O2.

Wrong, it make sense that 40ppm could be oxygen which is replaced
with CO2. As stated above.

But that's irrelevant to the point.

It matters not one jot whether or not "40ppm could be oxygen" if the
oxygen level is able to reach higher levels than the fish require
whether or not there's 40ppm CO2.

That is, suppose your fish want 100 units of oxygen.
Suppose that without CO2, your water can hold 900 units oxygen.
Suppose with CO2 the water can 'only' hold 897 units oxygen.

Now, will the fish be unhappy because there are 3 units that "could be
oxygen"?

Besides which, you should test some tanks. When I've done so, the
densely planted tanks with CO2 injection have had significantly higher
oxygen than the largely unplanted tanks. I think you're assuming that
all water is always fully saturated with gas, and that simply isn't
true.

regards, Ian SMith
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