Sensor performance


#1

Hey everyone! New to the group! Some collaborators and I are interested in building a food computer. My profession is in oceanographic/freshwater sensor networks; and in my experience when I purchase low-cost sensors I get exactly what I paid for. A pH or EC sensor that is finicky and unreliable. Anyone find any analog or digital pH or EC sensors that work for them? Something that can work for a month immersed in water without maintenance. I can recommend some great sensors in the multiple hundreds of dollars range, but curious if you’ve used one in the under $300 mark that you’re happy with.

thanks,
Jason


#2

@JasonA I think many people made the same mistake (myself included) and jumped into the DFrobot sensors. Then they discovered that the PH sensor is totally thrown off by the EC sensor and the readings become very unreliable in very little time because the sensors just don’t last. The only other choice for a sensor that has the capability to connect to a Pi/arduino that are decent are the Atlas scientific sensors. However these two sensors with isolation boards (so they don’t mess with each other) are much more expensive (>$400).

At the end of the day if your readings aren’t accurate then the recipe you’re trying to replicate could easily fail and the data you produce is useless.

Garbage in = Garbage out


#3

Yeah, no point in developing an automated system around sensors that don’t work. I tried making a multiparameter sonde with Atlas sensors a few years ago and was never able to get them to work well, so scraped the whole thing at nearly a $1000 (luckily my employer paid for it) and many many hours lost. I’ve seen that Atlas is now making “industrial” pH and EC sensors but I haven’t seen any reviews on them yet. Curious if anyone has deployed them together for monitoring. Or hoping the folks at MIT have figured it out.

But the RPi can handle any sensor with a serial output (adapted to USB). I’ve got several RPi’s acquiring data from some pretty sweet sensors (YSI EXO, Satlantic SUNA, Turner C-Sense). Great performance, but those sensors are in the many $1000’s each.


#4

This isn’t quite an answer to your question, but I’ve had good experience of using https://www.seneye.com/what.html in aquaponics. It’s a colorimeter with consumable slides which last a month.

Open source work has been done: https://iorodeo.com/collections/open-source-colorimeter but it’s not yet designed for continuous immersion like the seneye. It’s unclear to me if you could DIY your own slides.