I really like the Fluval for the options it gives me on placement as well as the ease of refilling it when the water gets dried out. I use it inline with a Griggs style reactor and down low so when the CO2 does dry the water out and I do want to check bubbles, I find it very easy to just unscrew the lid a tiny bit to let the gas out and water will flow in through the CO2 tubing from the reactor. As long as the gas is sealed, I use no check valves and just let the gas keep the water out of things.
I much prefer having the things I don't need to get to very often located way in the back with the things that I check like the bubble counter or needle valve located up front.
If I went back to using a check valve, I would add it between the bubble counter and the needle valve.
This is my current setup on a 125 gallon . The CO2 comes though the reg to item 1, a Clippard solenoid, up to 2, a Fabco NV-55 and down to 3, the Fluval bubble counter. From there the line goes around the back of the CO2 tank to the reactor.
With this arrangement, I can change tanks without fear of breaking things. I unscrew the reg and lay it and all the "delicate" parts to the left out of harms way. Drag the hulking 20 pound tank out and off I go. I hate to work with the fear that one slip might require replacing some expensive part or another.
