I'm working with a CitSci group in Eastern OH trying to develop a water quality sensor network to monitor changes in TDS in peoples well water and in local springs. We are the new dumping ground for the waste brine from fracking in PA and OH. Massive amounts being pumped into injection wells in our area so we are trying to get ahead of the curve on monitoring change. Need to keep the cost of the sensor/logger package under $20 as we are working with a very small budget. Planning to use the promini logger from the Cave Pearl Project as Ed seems to have worked out all the issues with that brilliantly. I've seen some threads here for different sensors but they seem to stop a couple of years ago. Anyone still working on this problem, or have any guidance for development of a low cost option?
Hi! The simplest (and cheapest) conductivity sensor I can think of is the Coqui-- we have a recent blog post about it here, and I would imagine with some tinkering it could be used with a logger, but as Chris suggests, if you're planning to use something on site, you may not need this part. @kanarinka is one of the people behind the Coqui, perhaps she's got some suggestions?
I've successfully used the DFRobot TDS/conductivity sensor combined with the a Mini-Pearl system. The Coqui was much too noisy. My Arduino setup was very similar to the setup suggested by @cfastie. I did not seem to have a problem with noisy measurements that were noted by Chris. However, this may have been due to a lower sampling rate over the 3 months that my unit was deployed. My major problem was related to moss and nutrient buildup on the probes; this in turn was likely due to drop in water depth and over exposure to sunlight. My sampling area was hit by a major drought (down to single digit CFS). I am also investigating (or will soon) use of a non-SD card solution. My goal is to have a rec'r in a 'wand' that I can pass over the unit and 'suck' the data off the unit. I won't be back on either of these until spring due to some continuing, rather serious, health issues, a change management of the watershed of interest, and then the spring thaw here in the Rockies. I hope to resurrect the Willow Creek and will either update or seriously gut the related write-ups.
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Hi, MadTinker, thanks for the info here. I was just wondering if you meant that the Coqui itself was noisy, or if you're referring to noise in the data -- thanks! (funny question i guess).