I've been growing Roma tomatoes now for 8 years. When growing tomatoes, pH levels can make or break the flavour!

I have been looking for an automated data logging system for my nutrient/water tank. I want to dump all the readings to a MySQL database.

I have a 45 gallon food grade drum used to store my nutrient solution. I would like to log/monitor the pH and Temperature and any other useful readings I can get (o2, co2) from this tank using phidgets.

My questions!

Can I keep the pH probe submersed?
Can I use the temperature module and pH module in the same drum.

The .pdf of the pH users guide talks about electromagnetic interference.
Will I need to remove a submersible pump from the drum to get reliable readings?

Can I use PhidgetInterfaceKit 0/0/4 to start/stop my pumps and sprayers?


If anyone has experience with garden/hydroponic automation and has great input I'd love to hear from you as well.


Thanks so much for reading my post and I welcome all responses!

Some PH Probes can stay immersed continuously, most cannot. You'll have to do some research on this.

If you put a thermocouple in the tank at the same time, you'll want to use a thermowell (usually an insulated stainless rod, or even just a piece of plugged plastic pipe to prevent electrical interference.

I don't know if your submersible will screw up the readings. Possibly.

Yes, the 0/0/4 can be used to switch your motors.

Chester

Chester,

You made my day!

Based upon your advice I went looking. And found:
http://www.aquaticeco.com/subcategories/1878/In-Line-Submersible-pH-Electrode/
It looks to have a regular BNC connector. I'm sure I'll have to test it out to know for sure it it will work with the phidget. Do you see anything blatantly wrong with the device above?

For my application do you recommend the Humidity/Temperature Sensor or the Precision Temperature Sensor. Could I use the humidity sensor to take ambient readings?

Also, could I use the Differential Gas Pressure Sensor to monitor the amount of solution in the tank?

Lastly, I have two water pumps(120AC) and two air pumps (12v DC), i want to control. Will I need to order both the PhidgetInterfaceKit 0/0/4 and PhidgetInterfaceKit 8/8/8 for my project?

Your PH Electrode looks ok.

If you use our temperature sensors, you have to figure out how to make sure the board is the same temperature as the water, without actually putting it in the water.

I don't know how the gas pressure sensor would monitor solution.

You could use both the 0/04 and 8/8/8, or get 3051 dual relay boards and control them from the 8/8/8.

Chester

Could I run a probe into the barrel?


I was thinking I could run an air tube to the bottom of the tank, over the top lip of the tank and calculate via the changes in pressure.

But then again I am a baker and vegetable farmer by trade, not an engineer!



Which would be the better choice? Would one be easier to add additional pumps/lines to?

Thanks!

Hi
I have just set up a web site to distribute my Phidgets base hydroponics and irrigation software. I hae not yet added in pH monitoring but it is on the list of todos. My site is www.peterphrastus.com

Hi Spider, I tried to see your Web Site about hydroponics system using Phidgets, but I can´t access, message “This link appears broken”. I´m interested, please could you confirm how could I consult it?
Thanks
Philippe Mandar, Caracas
phmandar@cantv.net

Hi

The website is at www.peterphrastus.com. Is it a particular page you cannot access or the whole site? Please let me know if you continue to have difficulty. Please send the page address you are having difficulty with.

Spider, it´s at www.peterphrastus.com that I cannot access

I click on the link in your email and the site is there just fine. I don't know what the issue is. What browser are you using?

Works fine for us.

Chester

I have been researching this subject for quite some time. There are many factors influencing pH and EC inline monitoring. There is the probe life, friendliness of the solution, electrical interference, cable capacitances and transmission of the signal to the Phidget. It is my understanding that the industrial 4-20ma spec is robust for transmission and less susceptible to spurious signal injection on cables connected to controllers. I have located a dual pH/EC transmitter here:

http://www.automatedaquariums.com/h_98143.htm

It is available in both 0-4v and 4-20ma versions. I believe the 4-20ma can be converted to 1-5 volts by putting a 250ohm precision resistor across the signal at the Phidget analog input. Can anyone confirm my understanding. Probes are also available at this site that are hardened to continuous monitoring of salt solutions. There is also a 4-20ma pH monitor transmitter at this site:

http://www.automatedaquariums.com/h_931700.htm

The advantage of this application is that there can be extra 8/8/8 analog ports available as the digitals tend to get consumed faster in apps.

As an extra bonus, the site sells reasonably priced peristaltic pumps:

http://www.automatedaquariums.com/dp_101.htm

One issue is that they do not ship to Canada. This is easily overcome if you know someone in the US who can mail your order to you.

Hope this is helpful.

This looks quite interesting. I wonder if it could be interfaced to the Phidget? How does one deal with the -2 to +2 voltage range? Anyone have ideas?

http://www.omega.ca/shop/pptsc.asp?ref=PHTX21&flag=1

Thanks

4-20mA is certainly a great way to send an analog signal a long distance.

Chester

After slogging through many sites, I found the whole gamit of parts in Canada to add pH and EC monitoring and maintenance to HydroHomeSoft.

Transmitter and EC probe

http://www.omega.ca/shop/pptsc.asp?ref=CDTX300&flag=1

pH electrode

http://www.omega.ca/shop/pptsc.asp?ref=PHE4200&flag=1

peristaltic pumps

http://www.omega.ca/shop/pptsc.asp?ref=FPU100&flag=1

SSR for 110 VAC

http://www.omega.ca/shop/pptsc.asp?ref= ... 660&flag=1

Now to find a couple of precision 249 ohm resistors (that will keep the upper voltage just under 5). After that, its just a matter of software!!