Join Date: Dec 2005
Location: Toronto, Canada
As you pointed out, I've seen people tilt their reactors to maximize contact time between CO2 and the water column. Normally this has been done on reactors that seem to have been designed to be used vertically, which leads me to the conclusion that the reactor is not designed for the water flow rate being used. You may have also noticed people reducing the flow rate on their pump's output (the reactor's input).
If your flow-through reactor has its input at the bottom with output at the top, regardless of where you input the CO2 it will quickly rise to the top and have a greater chance of passing into your tank in bubble form. That's why you'll see reactors designed the other way around. CO2 and water input at the top with output at the bottom. The CO2 will naturally rise, but the water flow is constantly moving down. This creates greater suspension and more time for the gas to disolve into the water column. There are variations on the theme, but you shouldn't run any design upside down from the way it was intended to be set up.
Lastly, inserting CO2 into the bottom of the top-down design will likely be counter productive as the water flow will force CO2 bubbles into the output line before they've had a chance to disolve.