Regulator/needle valve question for calcium reactor

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I am setting up my new calcium reactor, up till now I have done kalk and 2-part.

I had an old regulator and needle valve, I just realized it is junk, the needle valve won't adjust well, the regulator I am not sure about, so I'll buy a new one.

I am not running it on a controller.

Should I just get a regulator with needle valve or should I get one with a solenoid as well.

Even though I don't use a controller I was thinking the solenoid might help in case of a power outage, preventing the calcium reactor from getting filled up with Co2 which could cause an air lock when the power comes back on.

Never having used a calcium reactor before I want to hear advice from people with some experience.