Tag Archives: DIY Hot Tub Monitor

Build your own pool and hot tub monitor with ATmega328

SpaSitter is an open-source monitor that provides you with access to water conditions right from your smartphone.

Lounging in the pool as you bask up some sun and sitting in the hot tub after a long day at work may enjoyable, keeping up with the maintenance of them not so much. Having grown tired of monitoring the water chemistry of his aquatic area, Instructables user “bhuebner” decided to develop an open-source device that would notify him of water conditions in real-time, all through his smartphone and a web interface.


The aptly named SpaSitter is built around an ATmega328 based Nanode (essentially an Arduino with Internet connectivity) and Xively’s easy-to-use API. Three sensors housed inside a waterproof box are connected to the Nanode and placed in the hot tub or pool to remotely measure pH, oxidation reduction potential and temperature. Once collected, this information is uploaded to Xively where the data is tracked over time and displayed in graph form.


After a little calibration and testing of its probes, the Maker configured his system to send emails and text messages to his smartphone whenever the water levels began to dip. At the moment, he still needs to put the chemicals by hand whenever attention is required, but hopes that in the future he can automate this process as well.


Want to build your own spa monitor? Check out the Maker’s step-by-step breakdown on Instructables here.