It doesn't matter really, but I would give the co2 reactor more tubing, this gives the co2 bubbles more dwell time to dissolve.
Try with two smaller canisters. I think it would have better flow.Do you guys notice a significant flow reduction with both the inline reactor and heater on the same line? I'm designing a tank and I'm not sure if It would be better to go with 2 smaller canisters with the reactor on one and the heater on another or put them both inline with one larger filter.
Any experience/suggestions?