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5 lbs of CO2 Gone

Mike wrote about having to use 3 bubbles per second to get the proper amount 
of CO2 into his 55 gallon tank.

I have a 100 gallon acrylic tank that I set up at the end of April.  It is 
the first tank on which I have injected CO2 via a compressed air tank.  I 
could not believe how little surface turbulence it took to drive off the CO2. 
My tank has a built-in prefilter, which I keep covered.  The other two 
openings in the top of the tank are covered with Lucite panels.  The water 
drains into a large trickle filter on which I have taped all of the edges so 
that the filter is sealed.  The water is returned to the tank via spray bars 
which are submerged.  I ran quite a few tests and discovered that even with 
an essentially sealed system, that no matter how high my CO2 bubble rate was 
that the CO2 got driven off if there was any rippling of the water surface.  
I eventually had to reduce the flow of my water return pump to about 25% of 
maximum to reduce the surface currents to a point where the CO2 was not 
driven off.

I am currently using one bubble per second on my tank which with a KH of 3.0 
gives me 9-12 ppm of CO2.  This is approximately 1/6th of the amount of CO2 
that you are injecting per gallon per second.

A simple test that you can perform would be to measure your pH, then shut off 
your Emperor filter and then measure pH every ten minutes.  I think you will 
find the pH dropping rapidly.  At that point reduce the flow of CO2.  Keep 
measuring pH every 10 minutes and adjusting the CO2 accordingly to achieve 
your 6.8-7.0 range.  Once that is achieved compare your new bubble rate 
versus your normal 3 bubbles per second rate.  That difference is the amount 
of CO2 your Emperor filter is driving off.

Roger Gordon
San Diego, California