Found my CO2 leak

I assume this is the solenoid:


That looks like it uses a nut at each connection. If so, these usually work by you pushing the nut onto the plastic CO2 tube end, pushing a little metal tube inside the end of the CO2 plastic tubing, then pushing that end into the solenoid fitting and screwing the nut down a bit more than finger tight. I can't tell for sure from the photo if this is the type of fitting you have.

 

The photo I posted is from the Red Sea website. I haven't seen anything like what you have, but I suspect those red rings are supposed to be inside the nuts on the ends of the solenoid, so tightening the nuts squeezes them down onto the tubing. And, I have to wonder if that connection is intended just for rigid tubing, not flexible tubing.

 

vaughan. They are 'push fit' ones. Similar to industrial airlines (but much smaller) where you clip the hose in and the red bit locks. My reg had one of these but I unscrewed it and my needle valve screwed straight into where the push fit had been. lucky me. lol

I have a solenoid like the one you linked to with the nuts that screw over the barbed inlet/outlet fitted inline. Very good. However mine is from Lunapet/Aquarianversand on ebay. Half the price and exactly the same in design.

AC

 

The description of the solenoid says:
CO2 Solenoid Valve

"This small and reliable valve is for use with a pH controller or timer to automate the input of co2 for natural planted aquariums or calcium reactors. For use with a regulator with reduced pressure below 5 psi. Spring loaded quick fit connections make it easy to attach co2 resistant tubing. Tubing slides right in for tight and secure connection"

I think the bold, underlined part is the problem. Our regulators rarely hold a 5 psi setting, and sometimes even a 10 psi setting isn't too stable. My guess (my latest guess!) is that your CO2 regulator outlet pressure is just way too high for the fittings the solenoid has.