Ideally most throttle the pH controller to match the use by the tank.
That way if the solenoid sticks open, they do not gas their fish, but then the trade off is slow response times to depletion.
There is always a trade off.
The one I do not like: high CO2 at night.
If I have high CO2 during the day, it's off set by high O2 levels from the plants.
Not so at night time.
Chronic high CO2 cannot be a as good as a daily spike along with a spike of O2.
Just because the CO2 at night does not kill the fish, it remains to be seen if it's not bad for them as well over the long term. Few looks at the sublethal effects of toxicants at higher levels.
I'm a CO2 conservative today, but at one point, I was adding more than most anyone.
I add a lot only during rh day, the control is a needle valve which is very easy to adjust. More plant biomass as the tank grows, the more CO2 demand and the more gas I add.
You can set the pH controller fraction, the switch plug in, and add a lighting timer there. That way the pH controller only added CO2 during the day and maintains it.
pH probes can fall out of the tank.
The elctrical solenoid or unit can break etc.
Needle valves are cheap and reliable overall.
Like a Regulator/gas tank.
pH controller is an added expense that certainly no one needs, I do not think it gains anyone an adavtange, but seem to assuem that it does because they sell you on "automated CO2, pH stability and control" and 100+ $ later, you try and find some value yourself
I do use a pH monitor, they(controllers) are good for that, but not exactly portable tank to tank really. The control function is the needle valve and the solenoid that turns on for 10 hours a day.
Those tend to be pretty reliable.
Fish can certainly be fine and okay in both cases, but you know less CO2 at night has to be better for the fish...........and with all the whining and carrying on folks do about excess NO3's etc............I find it odd they have no issues adding lots of CO2, Amano is certainly guilty of this.
the real question that remains unanswered is what are the sublethal effects over time on fish/shrimps etc.
I see ADA's tanks and I really wonder why they have such few fish, a very commmon comment by many, and I cannot help but think they all got gassed.
The tanks I have are either test tanks and I do not have any fish, or they are packed in general.
I liked fish before I got into plants, one does not replace the other, they complement the other.
Some place plants primary or fish primary.
I focus on both.
Regards,
Tom Barr