I'm sure there are a ton of variables here but I'm not sure where to start to correct this? I have SMC needle valves and 2 PVC reactors plumbed after my Mag 18. . I placed check valves right before the reactors and another set after the needle valves. I have a Milwaukee MC 122 pH controller. Every time I come home from work my bubble rate is all over the board. The CO2 has been running for about 3 hours by that time and sometimes the bubble counter is somewhere around 5 bps, I can't really tell at that rate but its consistent. Thats where i want it. Two days later one bubble counter shows nothing. The next day both are fine. I've replaced the check valves several times thinking there was some sort of backpressure issue but that hasn't helped. What's going on here?