I've roasted 3 clippards. One recently was stuck and would open after 1-2 hours, so the 1st part of the lighting cycle, no CO2..........
I used a Reactor below and rarely look at it, so I did not realize there was an issue, the tank had some signs of poor CO2, all my other tanks where done the same light(same PAR, same sediment types, similar stocking levels of fish, plant density, same ferts added, same water changes etc).
I modified current for a bit to see. That did not help much.
Tried several slow modifications of bubble rates and watched etc.
I leave in the morning before the cO2 comes on for this tank so when I checked later in the day for issues, I was fooled.
I caught it a couple of weeks ago. Took the valve apart, it was sticking pretty bad. I replaced it, the tank is doing much better already.
There's the rod, the chamber and the electrical part, any of these 3 things can fail. Without a data logging CO2 measurement, it can be very tough to tell what is going on. Gave me a world of grief.
But, I knew I could rule out some things and isolate it. This made looking in the right spot much easier, I also know what poor CO2 looks like, but it got me there, since the sucker was open and running fine when I'd get home.
If CO2 can get me, it can get anybody. There's a lot more to CO2 "than adding it", "or adding more". It's nailed me, it's nail Amano(ask him), anyone that's done this hobby long enough. Reef folks using Kalks and CO2 also have some serious words about solenoids.
I guess a multiple redundant system will prevent adding too much, but not adding enough or a sticking valve that does not open when it show, would require a more complex system.
So I got nailed.