I've been tempted to invest in a pH controller in an attempt to keep CO2 levels stable at around 30ppm.

I've had good results with 24/7 injection before in my 33 gal. This time I'd like to save on CO2 refills (500g cylinder) and either go for a solenoid linked to the lights or a pH controller.

Any thoughts on 24/7 vs. solenoid vs. pH controller?

Forgo the pH controller and turn the CO2 on with a solenoid only during the day peroid.

That's what both Amano and myself have done and most every scaper in recent times does.

Regards,
Tom Barr

Cheers Tom. Saves a few pennies.

An advantage of a pH controller plus a solenoid, is that you can increase the CO2 bubble rate much higher, and arrive at the desired pH faster than if you use a lower bubble rate that itself controls the pH. I wouldn't spend the money for a controller to do that, but if I had a controller already I would add the solenoid to be able to do this.

I'm pretty much in Agreement with Tom, and VaughnH. I'd add that a PH controller is only as accurate as the guy that calibrated it. (Ask me how I know) That may seem like a no brainer, but many times technology only provides the "Illusion" of control ! ;^) A solenoid on a timer is more than sufficient. A controller is just as likely to be another weak link in the chain. There's no substitute for conscientious maintenance. A PH Controller isn't an insurance policy. Found that out the hard way !!! ;^)

Thanks for the feedback guys.

One quick question - is there any benefit to having the CO2 on for an hour or so before lighting so the desired CO2 levels reached at photoperiod start? Or do the plants take time to commence their photosynthesis and therefore don't require higher CO2 levels at the start?

Well, a little of both really, it would be best to make sure, thus add CO2 prior to the light coming on to get things really cranking right away.

If you have a larger tank or a long CO2 line, this might be a better solution, smaller tanks, probably will not make much difference if you have a good sized CO2 deliverly method etc.

Regards,
Tom Barr

Yes it would be faster but it will also kill your fish if there is a malfunction. I have a pH controller and I only use it as a pH monitor and a fail safe to turn off the co2 if there is a manlfunction.

I set the bubble rate to drive the pH to my target and then set the controller to turn off the CO2 if the pH drops .3 or so below my target.

Is it worth the cash to by a controller for this? Probably not. I bought mine with the intent to control the pH and discovered it did not control the pH as consistantly as I wanted. The plus or minuse .2 in the controller was too much.

I love the real time ph reading on the controller however. If this one breaks I will definaty buy some time of real time pH monitor. If it only cost a few dollars more to add in a controller function I will get the controller just as back up.

Rick.

I tend to just add CO2 1/2 prior to the lights coming on, that adds plenty of gas during the photo peroid without the risk.

But yes, you can run a pH controller/solenoid adding CO2 at a higher rate for the day cycle also.

So adding CO2 to maintain a stable pH is really not the best of methods really I think. It works and all, but you get better results adding more and less fish stress at night when the lion's share of the 24 hours is low CO2 and relatively high O2.

Most folks run their light for 10-12 hours, so 12-14 are no CO2.


Regards,
Tom Barr

I didn't want to hijack the thread or anything.
I was wondering about this... running co2 without pH controller, won't it cause any pH crash or pH swings?