Part of the issues with running PH controllers is the pH in the water doesn't track the ppm of CO2 instantly. There is a lag there too. And, any controller has to allow the pH to vary a little in order to work. Otherwise, it continually hunts - turns on and off every few seconds - which isn't a great idea either. As far as I know most pH controller have a "on" setting and a different "off" setting, to avoid the hunting. The other thing with Controllers is the pH probe needs recalibrated periodically. If your using a Reactor, another issue you will have with using a controller is you can get a big overshoot on CO2 concentration. How? The CO2 collected in the reactor will continue to go into the water until it is depleted, some time after the controller shuts off the CO2. And, again, the water pH changes lag the CO2 concentration changes, further adding to the overshoot.
Here is some of my experience with a controller and how I would set it up if your going to use it. Again your using the fish to be the measure of how much is to much Co2.
Here is my input as someone who has used a pH controller for the past 5 yrs. Here are some observations during that time:
1. Slowly and carefully determine the stress point for your fish and shrimp. When you reach that point that they are showing stress measure that point in the water with a calibrated probe and meter. If that amount lets say is a PH of 6.0 then set the pH controller to turn on the CO2 at 6.2 and turn it off at 6.1. This will keep it within safe levels if your using a slower BPS. If using a higher BPS and a reactor give some more gap.. Say on at 6.3 or 6.4 then off at 6.2 or 6.3.
2. Fine tune the rate of injection to achieve the desired pH level in a relatively short amount of time. I adjust my needle valve several times during the life of my CO2 tank refill so that the gas is not injected for long periods of time (too low rate) or does not overshoot the desired level before the controller can turn it off (too high rate) thus stressing the fauna.
3. Check probe calibration regularly. I use 6 month intervals, but have rarely had to adjust.
4. Diffusion methods can greatly impact the rate of CO2 needed. I have used ceramic diffusers, reactors, and currently the new Atomic diffuser....and each method has required a different CO2 rate to easily keep the pH consistently at 6.1.
As usual, your results may vary. I just thought I would share my relatively long term experience here
Here is some of my experience with a controller and how I would set it up if your going to use it. Again your using the fish to be the measure of how much is to much Co2.
Here is my input as someone who has used a pH controller for the past 5 yrs. Here are some observations during that time:
1. Slowly and carefully determine the stress point for your fish and shrimp. When you reach that point that they are showing stress measure that point in the water with a calibrated probe and meter. If that amount lets say is a PH of 6.0 then set the pH controller to turn on the CO2 at 6.2 and turn it off at 6.1. This will keep it within safe levels if your using a slower BPS. If using a higher BPS and a reactor give some more gap.. Say on at 6.3 or 6.4 then off at 6.2 or 6.3.
2. Fine tune the rate of injection to achieve the desired pH level in a relatively short amount of time. I adjust my needle valve several times during the life of my CO2 tank refill so that the gas is not injected for long periods of time (too low rate) or does not overshoot the desired level before the controller can turn it off (too high rate) thus stressing the fauna.
3. Check probe calibration regularly. I use 6 month intervals, but have rarely had to adjust.
4. Diffusion methods can greatly impact the rate of CO2 needed. I have used ceramic diffusers, reactors, and currently the new Atomic diffuser....and each method has required a different CO2 rate to easily keep the pH consistently at 6.1.
As usual, your results may vary. I just thought I would share my relatively long term experience here
