OK Gentlemen and Ladies, sorry for the delay in replying. After disassembling my pool probe to take pictures I decided it was time to improve it a little. Originally the Fibaro was in several layers of freezer bags, each individually tie wrapped to all allow the wire to protrude, however of course over time they start to leak so I came up with an idea to make the sensor a bit more robust.
This is the probe in the pool, the chlorine dispenser is way too big in fact but I imagined the Fibaro sensor was bigger when I ordered it. You can see the probe floating in the water below, it doesn’t need to dangle so far but I was testing for the ideal depth, in my case the water is well mixed so depth didn’t really matter.
This is the Fibaro and DS18B20 out of all the protection:
The wiring inside:
My idea to improve the water resistance of the project; encase the probe in one of those medication tubes with a snap top.
Now I’m just waiting for the silicone to cure both on the inside and the outside of the cap. I will also silicone the cap into place before the whole unit goes back in the floater. As the battery seems to be holding up well (still reading 100% after >2 months) I don’t mind breaking the seal and resealing the unit when the battery needs to be changed.
Eventually I’ll fix the sensor under the pool margin stones, once I find a suitable box to put it in that doesn’t look out of place in a pool. I guess you could also place the probe in the filter intake pipe.
Alternative hacks I considered:
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An ESP8266 with a DS18B20 temperature probe. I ruled this out because I wanted a battery operated system and the ESP is quite power hungry and I don’t have the skills to write some complex code to get around this.
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An ESP8266 with a DS18B20 temperature probe and a solar cell on top of the chlorine diffuser to charge a battery. This would be a cool project that I might try one day.
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A Fibaro Universal Sensor - looks great but probably needs to be attached to a power supply for the 9-30v DC it requires. I didn’t calculate battery life for this sensor.
I hope this information is useful!