New grow room Autopot grow

Kola_Kreator said:

The mother nature CO2 generator is not suitable for maintaining optimal levels in a sealed grow room. Do you have a CO2 metre to monitor the levels? To run sealed you need bottles at minimum or an actual generator is better and you need to have a CO2 controller to regulate the ppm

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ryan s said:

Thanks for that advice!

Can you point me to any good ones I should consider buying?

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Kola_Kreator said:

Trolmaster are the standard in grow room controllers. You can buy a basic one just for CO2 or you can get something more advanced and set it up to do the humidify and temp too. For the bottles you can usually get them a lot cheaper at home brew stores than the hydro shops.

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ryan s said:

This is much cheaper. Would this work for my basic needs?

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Thank you.

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Kola_Kreator said:

That's pretty much all you need. Just make sure that the controller uses fuzzy logic. It's basically the programming which lets the controller dose the room without overdosing it.

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Billy the Mountain said:

There's no advantage to a fuzzy logic controller with a simple, linear system, like maintaining a target CO2 level.
A PID controller works about as well as you could hope for.

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ryan s said:

I ordered an A/c Infinity CO2 controller and regulator. I'm just now realizing that the two CO2 tanks I had were worth 600 dollars each. They got "thrown away," I believe. Well, another lesson.

The growgeneration nearest me rents CO2 tanks I believe, so I will be getting my gas there.

Thanks for all the input!

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StoneDHedgE said:

Don't tell that to my rice maker. Imho CO2 in small/medium tent grows is a waste of time and money. Nail every other aspect of growing first.

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Billy the Mountain said:

I know nothing about rice makers but have reasonable knowledge and experience writing control system software.
Again, a fuzzy logic algorithm has no benefit in a simple linear system.
A PID controller (Proportional Integral Derivative) continually calculates and error value (target - current) and self-adjusts to compensate.
The P term is the current error, the I term is cumulative error, and the D term is the rate of change of the error.
Tuning the PID terms can take a bit of trial and error but it's a proven and effective algorithm widely used in industry in similar applications.

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Kola_Kreator said:

You know a lot more than I do about control system software. Will the PID controller learn and tune itself to keep things stable?

I always thought fuzzy logic was basically what you are describing when talking about PID. What advantage if any does fuzzy logic have over PID?

Do all grow room control systems run PID at the minimum? Some of the cheaper prices control systems don't state which software they run.

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Billy the Mountain said:

I would guess a PID controller is used in most all commercial CO2 controllers and would be surprised if any of them used a true fuzzy logic system.
Fuzzy logic controllers are used in more complex scenarios where there's more "grey area"; things like medical diagnosis, image processing, stock trading, etc.; situations where there's a number of variables to be factored and there's more noise in the system. Controlling a relay based on a sensor input isn't one of them.

It's self-tuning in the sense that a PID controller will modify it's output to minimize error, but it's P, I, and D parameters are defined by the user.
You can tune how quickly it responds, amount of overshoot and ringing, and sensitivity; basically a compromise between speed and accuracy, but it doesn't normally change dynamically at runtime.

Hope that helps


Basic PID algorithm:
View attachment 5321465

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Kola_Kreator said:

Good explanation but poor understanding on my part. My grow shop only carries the trolmaster units which apparently use fuzzy logic. I can pick one up that does temp RH and CO2 for about 600. It works for because the grow shop will sort things that day out if there's any issues down the track.

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Billy the Mountain said:

I'm sure it works well but I still wouldn't be wowed by the fuzzy logic claim; I'd bet big it's just fuzzy marketing lingo.
The price seems exhorbitant, but I'm just a hobbyist with a few tents and like to build things.

From their product description:
a ) If the Fuzzy Logic function disabled, the unit will OPEN the output of CO2 device when the current CO2 level is less than setpoint, and CLOSE the output when the current CO2 level is greater than CO2 setpoint plus deaband value.
b ) if the Fuzzy Logic function enabled, the unit will fully OPEN the output of CO2 device when the current CO2 level is much lower than teh setpoint. When the CO2 level is closing to the setpoint, the unit will calculate and send PWM signal to control the output of CO2 device. The PWM cycle is 5 seconds.

What they just described in b) is a PID controller, i.e. the output is used to vary a PWM signal.
I use the exact same method to control a resistive heater for my alcohol extractor. The PID controller lowers the PWM duty cycle as the target is approached. Once the target temp is reached, it doesn't vary by more than 0.25C, even thought the heater is either fully on or fully off.

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