Vegetish

It can be found in Step 4: Upload Sketch. But be warned that the code I wrote three years ago might not be compatible with the current version of Blynk, and will need to be updated

Sorry for the late reply. I remember I had similar issues, and I believe I found it was because of limitations to the current draw from the arduino mega board. Bypassing the power supply from the arduino to an external supply might help.

Please forgive the late reply. The Atlas sensor are more stable in my experience also, albeit more expensive. I've had a sensor setup with these cheap probes running for 3 months with recalibrations bi-weekly, and I would say it was accurate enough for this application. They do have a tendency to break down over time though. Around 2 out of 8 probes have broken down in a matter of weeks.So yeah, if you want a stable and robust rig, go for atlas probes.

​Thanks for your comment. :)The CO2 source that I used was a big CO2-flask that was already set up in the lab where this regulator is installed. I know brewing shops sell these, and it's definitely available from several other retailers.The coupling from the CO2-flask is pretty simple. Just make sure to regulate the pressure and flow into the valve. The particular valve I'm using has a max pressure rating at 0.7 Mpa/101.5 PSI. You need an adapter to connect a pnematic/PTFE tubing from the flask to the valve.Do keep in mind that CO2 is not the ideal pH regulating agent for all systems. I plan to use this same regulator in a hydroponic system with a peristaltic dosing pump that delivers phosporic acid to the water to lower the pH.I could probably make a whole instructable just for the alg...

​Thanks for your comment. :)The CO2 source that I used was a big CO2-flask that was already set up in the lab where this regulator is installed. I know brewing shops sell these, and it's definitely available from several other retailers.The coupling from the CO2-flask is pretty simple. Just make sure to regulate the pressure and flow into the valve. The particular valve I'm using has a max pressure rating at 0.7 Mpa/101.5 PSI. You need an adapter to connect a pnematic/PTFE tubing from the flask to the valve.Do keep in mind that CO2 is not the ideal pH regulating agent for all systems. I plan to use this same regulator in a hydroponic system with a peristaltic dosing pump that delivers phosporic acid to the water to lower the pH.I could probably make a whole instructable just for the algae bioreactor, but the idea for this instructable was to show how to build a simple and cheap regulator that can be used with any pump or valve with most pH regulating agents, perhaps with a slight modification to the code. ;)

Also, In other cases you would be more dependent on pH elevating agents to regulate the pH. It all depends if the life in the ecosystem generally lower pH or elevates pH.

Also, In other cases you would be more dependent on pH elevating agents to regulate the pH. It all depends if the life in the ecosystem generally lower pH or elevates pH.