Don't run airstones when running
CO2, you are off gassing
CO2 and creating un-stable
CO2 levels which to some, is worse of than no
CO2 at all. Run them on a timer to run at night to help with gas exchange. You can have high
CO2 and high
O2 in the tank at the same time.
Ensure
CO2 is dropping the pH of the tank water a full 1.0 – 1.2. To do this, measure the pH of tank water with no
CO2 dissolved in it, and then measure again 2-3 hours after
CO2 has been running. Ensure the drop in pH is a full 1.0-1.2. If the drop is not there yet, slowly up
CO2 over a few weeks until at least a 1.0 drop is achieved, and watch fish / livestock carefully. Adjust
CO2 down if you notice fish gasping at the surface and consider running an airstone at night when pushing a 1.2 or greater drop. For example, a tank water pH of 7.5 with no
CO2 dissolved in it, should reach a pH of 6.5 – 6.3 for
CO2 to really shine, and for maximum plant health.
Consistency in
CO2 levels is key to plant health. Keep
CO2 levels as stable as possible once a desirable level has been reached.
On a 125... I would recommends buying a Dwyer RMA-150-SSV flow meter, this will allow you to track gas usage better than counting bubbles, I would think you need to be north of 10 bubbles per second to achieve a 1.0 drop in pH. Note that in any tank, a 1.0 drop would indicate
roughly 30ppm of
CO2 which is a good target to aim for. Run your filter outputs to create a small but noticeable ripple effect across the surface of the tank water to allow for good gas exchange, but not too much
CO2 loss.
This would be ~25ppm - 40ppm actual, impossible for hobby grade equipment to tell, but note your drop in pH and keep it consistent. A $20 pH pen that can be calibrated off of Amazon is a great investment to a higher tech tank.
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