Gravity: Analog TDS Meter Sensor Kit for Arduino - 83cm Waterproof Probe with Anti-Polarization Design, 0-1000ppm ±10%, Water Quality Testing for Hydroponics/Aquarium/Home

I wonder things, such as ash or bad rain, wouldst alter the water herein, that lieth await of measure. The "sensors", purchased from those of yonder great rainforest, have arrived.Doeth having so much waiste change our waters in ways we cannot imagine, yet may still divine?Valuing my fish and their health perhaps more than I do you and yours, reader, I shall not at mine own hand test these hypotheses. I shall defer to expert authority. Yet I would still measure, and have a little bird tell me in mine ear when such measures ring warning.

This is a pretty good budget EC sensor for small experiments. EC/TDS are highly dependent on water temperature so it would have been nice to have a DS18B20 included in the kit. There is a bit of extra calibration required so be prepared to do a little math when you hook this thing up. Luckily, the code samples were very useful and provided accurate readings when calibrated to the correct K value. This is perfect for my project right now, but I’m probably going to upgrade very, very soon... I’ll need a higher range beyond 1000ppm in the late summer.

I purchased one of these to add to my hydroponics system -- it seemed like a neat measurement to track. HOWEVER, monitoring TDS for drinking water where TDS levels are (hopefully) in the 0 - 300 ppm range is entirely different than monitoring nutrient solution for hydroponics where TDS levels for most plants START at 1,000 ppm and range up to over 3,000 for some such as tomatoes! Unfortunately, these levels are way outside of the range for this probe. I have not yet found a packaged probe capable of measuring TDS beyond 1000 ppm and am beginning to think I'm going to be looking at the DIY projects again (which didn't seem too bad, but involved a lot of calculations).In terms of accuracy, this probe seems reasonable UNDER 500 ppm and I was able to get reasonably consistent readings compared with a typical "pen" probe for solutions with different TDS concentrations. Some advice out there suggests calibrating it using something like 700 ppm solution, but my experience has been that results are much better calibrating it with 200 - 300 ppm solution and taking any measurements over 500 "with a grain of salt" (there's a chemistry joke "dissolved" in there somewhere).The GravityTDS library isn't too bad to use, but there was a variable type issue that needed tweaking (int to uint16_t). Others have reported different niggling compile issues, but this is what I had to fix. I looked through the source code to better understand what it was doing and was more comfortable using it. (The sample code that doesn't use the library is pretty chonky -- more complex than needed IMHO.) NOTE! The library code uses a few bytes of EEPROM memory to stash a calibration constant. You can set the address so it doesn't stomp on other stuff, but I didn't like that it was quietly in there waiting to trash my other EEPROM data without warning -- I found it by accident.Anyway, the probe is fine for what it is intended for -- monitoring DRINKING WATER purity. Cheers!