DISSOLVED OXYGEN KIT

Atlas Scientific is on a mission to make high-quality sensors for environmental monitoring available to everyday hackers and makers. All of their kits are easy to calibrate and connect to your microcontroller-based project.
There are basically two easy ways to measure oxygen dissolved in water: You can guess and then insist that you measured it, which has the obvious disadvantage of being wildly inaccurate; or you can just use the Atlas Scientific Dissolved Oxygen Kit.
The Dissolved Oxygen Kit comes with everything you need to take accurate, full-range D.O. readings for your environmental monitoring, hydroponics, wine making, fish keeping… well, any project where you need to continuous or intermittent Dissolved Oxygen readings. There’s a simple 5-second calibration that is required before you can deploy the probe (calibration solution is included with the kit) and it can be immersed and operating continuously for 12 months before recalibration is recommended!
The Dissolved Oxygen circuit returns data in the form of Mg/L to two significant figures. Readings can be taken either dependent or independently of temperature or conductivity and the probe will function correctly in fresh-, salt- or brackish water.