Bill, that's why this reactor is cool, it was the only way to use a reactor and still throttle CO2 on/off using DIY CO2.

No CO2 is dssolved when the powerhead is turned off, so sinmply adding the powerhead to the light timer achieve the goal, of dosing CO2 only when the lights are off.

This way the CO2 DIY gas never stops flowing and safely burps out to the air above when the power head is stopped. Same deal with a powerhead used alone also, this just diffuses the flow downward and gently and maximizes the dissolving of the gas till lots of O2 is present.

You can use a solenoid set up with a DIY CO2 system though without blowing the cap off etc.

You use a Tee, the Tee branch that comes down, the verticle line in the "T" has the solenoid attached, the straight part of the T goes to.from the DIY CO2 and the reactor.

When the solenoid valve shuts ooff ansd closes, this pressurizes the line the gas goes into the reactor, when the solenoid is open and "on", the gas vents out to the air.

It's called reverse solenoid application.

I did this but powerheads cost 9-12$, solenoids at the time cost 40$.

To my knowledge, I am the only one that has ever done that with DIY CO2 + solenoid on plant tanks.

There's no need though since the powerhead controls the on/off part.

Regards,
Tom Barr