[APD] Hagen DIY CO2 System - Are All Bubbles Equal?

[Billinet at aol_com]

Are old bubbles different from young bubbles?

I have been using the Hagen system for about a month.  After a minor 
modification and some experimentation to determine the proper fuel mixture, it is 
working as advertised, putting out about 20 bubbles a minute.  The CO2 level in 
the evening, according to the chart, runs between 12 and 20 PPM, which is OK for 
a low light tank.  The plants are showing improvement.

My question concerns bubble size.  When I start with a new mixture, it soon 
is producing about 20 bubbles per minute.  These float upward, one by one, 
getting smaller as they near the exit.   But after about 4 or 5 days the bubbles 
start combining at the point in the diffuser at which they exit the tube.   
After two or three join forces, the combined larger bubble floats upward, getting 
smaller as it goes but never as small as the new mixture bubbles.  
Nonetheless, the CO2 level seems to remain more or less constant.

Does anyone know why the bubbles produced from the older cultures combine 
like that?  I would think that the amount of CO2 per bubble would be the same.  
As the yeast dies (from alcohol poisoning?) the number of bubbles per minute 
drops off,  but I would think that the size and content of each bubble would 
stay the same. 

I have tried cleaning the passages of the diffuser with a toothbrush but this 
doesn't seem to have an effect.  And lately I have been starting new cultures 
without that cleaning, and the bubbles start small as described above.

So, why is this happening?

Thanks.

Bill
_______________________________________________
Aquatic-Plants mailing list
Aquatic-Plants at actwin_com
http://www.actwin.com/mailman/listinfo.cgi/aquatic-plants