i have recently set up a co2 system, co2 bottle/with a small glass diffuser in the aquarium....there is a bubble counter attached right at the co2 bottle....the co2 is set to turn on/off with the lights by a timer....i placed one of those hagen check valves in the line....but after the first night, in the morning the bubble counter was filled and the hose was full of water......it was working during the day....but the check valve didnt do its job in the night.......is this not the right kind of valve........what kind of valve would work......and does it matter where in the line the valve is placed(middle, or close to one or the other end)