Where have I been? Why have I not heard of this product before?

It is called a NODEMCU (pic below) and it incorporates the ESP8266 wifi chip. (I paid about £10 for it with carriage from eBay)

It has a small micro-processor chip on a board with a Wifi chip. (plus voltage regulator and mounting board etc) I have just received it today (2015-12-10)

It, apparently, will alleviate me having to buy an arduino with wifi shield for my "Soil moisture check project" {As of Dec2015 I have not yet published this on my home automation project log}. I can now fix a moisture sensor (pic below) (also from eBay) to this little beauty and (with 3.3v of power) I can send the result straight to my IoT (Internet of Things) server running on a raspberry pi via WiFi !!!

So, all (!) I have to do is:

• write a little prog (with assistance from the web)
• upload it to the NODEMCU
• power it up
• attach the sensor

and I will receive {on my raspberry pi} little messages on the IoT server saying something like... "Sensor=1, 80.00" or "Sensor=2, 05.00" meaning, of course, sensor 1 = 80% humidity or sensor 2 = 5% humidity.

You may be wondering, dear reader, why am I interested in this being part of my Auto-Aquarium, well, the waste water from an Aquarium (during auto-water changes) is full of nutrients and I use it to water my plants with. They LOVE it. So as part of my auto water changes I will keep an amount of this waste water. When my Raspberry pi realizes that my plant pots are dry (via the above NodeMCU sub-project sending in IoT messages) it will pump some of this nutrient-rich water to the plant pots, probably about 10 seconds worth of water via a mini pump (a timed amount in order to stop problems of overflow problems).