Hi all, first post here.
I have some (very) basic experience with Arduinos (specifically an Uno, Mega, and SparkFun RedBoard so far.) Beyond Arduino I'd like to say that I also have basic electrical engineering knowledge.
I would like to embark upon a project that incorporates an Electrical Conductivity sensor, from which Total Dissolved Solids (in ppm) will be estimated. I see that Atlas Scientific sells kits for this express purpose (https://www.atlas-scientific.com/product_pages/kits/ec-kit.html), but at $160 I would like to find a cheaper solution, if possible.
I found two HM Digital TDS monitors, the SM-1 and DM-1 (see the DM-1 at http://www.amazon.com/HM-Digital-DM-1-In-Line-Accuracy/dp/B001EHAZGW/ref=sr_1_1?ie=UTF8&qid=1390336977&sr=8-1&keywords=HM+Digital+DM-1. The SM-1 monitors the TDS of one line, while the DM-1 monitors two lines simultaneously. Since they both retail for about $25 on Amazon, I'd like to get a DM-1, crack it apart, and hack it into an Arduino. Since the DM-1 has enough sensors to monitor two individual lines, this results in about $13 per sensor if everything goes according to plan.
What I know so far: it uses 2 x 1.5V button batteries, so I think that it should be able to operate comfortably off the Arduino's 3.3V pin; it uses an LCD to display ppm, so I should be able to somehow "intercept" that reading and store it for use in program logic.
Now, I don't expect anything to have done this exact thing yet. I'm not really asking "how do?," either--I just want to know if I should even bother trying to save $150 or if it's very unlikely that I'll be able to hack this together. If I order a DM-1, take it apart, and post some pictures, do you think I could get some help/guidance if I hit a brick wall somewhere along the line?