Placement of CO2 reactor

[Green Baron]

I would like to find out what is the ideal postion for either internal or external CO2 reactor. Should I put the reactor as low as possible, in the middle or as high as possible ?

[vinz]

For an external CO2 reactor, I'd say do not to put it lower then the filter itself. Try to keep the total hose length as short as possible.

For internal, depends on how it creates circulation in your tank and practicality. Close to the top is more practical as the filter inlet is usually near the top. But I dislike how the reactor outlet is always at mid height. What some ppl do is use elbows and hoses to divert the output to a rainbar or another outlet.