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Re: Are Plant Bubbles Really O2?

> Date: Thu, 12 Jun 1997 10:03:09 -0400 (EDT)
> From: Paul Chapman <chapman at SEDSystems_ca>
> Subject: Are Plant Bubbles Really O2?
[Snipped description of bubbly tank with lots of algae]
> I would think that a pile of plants producing that much O2 would be 
> growing like crazy and doing well.  But they were not.  Two possible 
> explanations came to mind:
> 1.  The bubbles really were O2 and were produced by algae covering my 
> plants.

I've seen this in brightly lit, unfertilized tanks for a few days after a
water change.  I expect the bubbles are produced by the algae on the
plants more than by the plants.  But, once one forms the bubbles, any O2
from the other just ends up in the bubbles anyway. 

> 2.  The bubbles were really CO2 coming out of solution, much like those 
> bubbles you see inside a tall, cold glass of Budweiser.
> Since I was using yeast CO2, and I saw no huge drop in pH, I doubt 
> explanation 2, but I haven't heard others describe bubbles coming out of 
> algae.

Explanation 2 is pretty unlikely.  I have seen bubbles form on algae - on 
surfaces coated with algae and within mats of hair algae.

> Has anyone ever tested the gas released from plants to make sure it really 
> is oxygen, and not just excess CO2 coming out of the water?
> Paul Chapman
> Saskatoon, Saskatchewan, Canada.

I too have noticed a lot of bubbling in tanks where there didn't seem to
be a corresponding amount of growth from either algae or plants.  I wonder
if this might be a sign of nutrient imbalance - the plants are capable of
photosynthesis, but don't have the nutrients necessary to build new
tissue, so the photosynthesized carbohydrates are either stored (probably
in rhizomes, etc) or simply lost back into the water. 


Roger Miller