Automated testing

Request new hardware or ideas for the controller

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Joined: Fri Mar 18, 2011 6:47 pm
PostPosted: Thu Oct 19, 2017 7:56 pm
All our expansion modules are analog and I use an analog to I2C chip, so not much different.
Roberto.
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Joined: Fri Jul 20, 2012 9:42 am
PostPosted: Sun Oct 22, 2017 5:36 pm
Cool so just a matter of cost on that probe and some math?

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Joined: Wed Apr 27, 2011 9:08 am
PostPosted: Mon Oct 23, 2017 11:58 am
Yeah, the Seneye will reportedly try and do it for $200. Also the accuracy of alkalinity value will be affected by the pH and CO2 probes accuracy.
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PostPosted: Mon Oct 23, 2017 8:15 pm
Yeah, for the price of the Seneye, it's not a terrible purchase. Just won't be able to automate anything off it or integrate it into the RA data. Maybe I'll figure out how to scrape it off the web interface and push it to a custom variable :)

If we could do the same it would be cool though :)

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Joined: Wed Apr 27, 2011 9:08 am
PostPosted: Tue Oct 24, 2017 3:40 pm
I checked on the probe that Roberto linked and thats about $7K. The probe from the research paper is about $720. The one I had linked is rated from 400ppm to 10000ppm which is out of our detection requirements. Average dissolved CO2 in seawater is around 350ppm. However when looking up the CO2 probe I get varying specs even though they look pretty much the same. In the following link the sensor is rated from 0-2000ppm but with an accuracy of 200ppm. The accuracy maybe reduced through longer average sampling. Not sure if it will be viable but I'll try and look some more. Absolute value of alkalinity will probably deviate a large amount, but possibly large sampling and weighing the final number by a titrated calibration value might work.

https://www.seeedstudio.com/Grove-CO2-S ... -1863.html

Tim

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Joined: Wed Apr 27, 2011 9:08 am
PostPosted: Tue Oct 24, 2017 3:54 pm
The following probe has better accuracy numbers.

https://www.tindie.com/products/Blueber ... sor-ee893/

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Joined: Wed Apr 27, 2011 9:08 am
PostPosted: Wed Oct 25, 2017 11:22 am
Here's a website that goes through the calculations for pH, total alkalinity, CO2 and pCO2. It does it backwards from what we would want namely obtaining CO2 from total alkalinity, whereas we would want total alkalinity from CO2 and pH. They also do an iterative process to lock down a converging pH value and alkalinity which is interesting possibly allowing us to get a more stable value if implemented. There is source code on one of the tabs showing the constants that he used and how he does the calculations in code.

http://biocycle.atmos.colostate.edu/shiny/carbonate/

Tim
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PostPosted: Wed Oct 25, 2017 8:30 pm
tngo wrote:The following probe has better accuracy numbers.

https://www.tindie.com/products/Blueber ... sor-ee893/


I like that this one is optical.

Posts: 133
Joined: Sun Mar 09, 2014 11:01 am
Location: Santos - Brazil
PostPosted: Fri Oct 27, 2017 4:16 am
I have a planted aquarium with CO2 injection. Would love to have one of this.

Rafa
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Joined: Sun Mar 09, 2014 11:01 am
Location: Santos - Brazil
PostPosted: Thu Nov 23, 2017 3:14 am
Any progress on that? Maybe we could open some kind of crowdfunding to help somehow?
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