Solenoid cycles on CO2 to reactor: how often is too often?

[sphelps]

I tend to have the opposite thinking, I'd rather it cycle more often than stay on for long periods of time. IME these solenoids typically fail off since they are NC and when left on for long periods they produce a far amount of heat. So seems to me having it stay on for longer periods is more likely to create a failure, especially one with it left open. I use to run my bubbles fairly fast for this reason, the valve would only kick on for 30 seconds or so before shutting off and then would stay off for longer periods until the pH recovered. While this did mean the reactor pH would drop a bit more than you guys are seeing it still maintained near perfect levels in the display.

I also seem to recall setting my target pH lower, closer to 6.4 as suggested by the media, which allows for a slower effluent and more efficient use of the C02.

[Delphinus]

That's interesting, thanks, I'll check the temperature of the solenoid when I'm home from work.

Mine seems to be settling out at 6.5 now although I was sort of hoping to target 6.6. If you ran fine at 6.4 then maybe I'll leave it as-is for now until I have a more substantial calcium draw (all I have are frags so far).

Here's a chart of the last 12 hours or so:
reactor_co2_ph_2.jpg

You can see that overnight I still had the bubble rate too fast and the solenoid cycled off/on until I checked in the morning. I did a *very slight* decrease to the CO2 flowrate at 8am (literally, I wasn't even sure if I had moved the knob) was all it took to keep the solenoid to stay on, except that the controller kicked it off when it hit 6.55 (the previous off setpoint). So I lowered the off point to 6.5 to see where it would settle and it seems to have coincidentally completely settled on 6.5 so the solenoid hasn't turned off yet.

I wasn't sure if I was going to try slowing the CO2 again to see if it would settle at closer to 6.6 or if I should lower the off point to 6.45 (I'm a little worried that if it settles right on the borderline then it might switch the CO2 off and then it will go all the way back up to 6.7 before it turns on again ... although you can see by the "up curves" that it doesn't take very long to raise the pH).