December 2014
I bought one of those Internet-aware soil moisture devices a few months ago. It worked great at first, but now the electrodes are oxidized and the readings are falsely dry because of the increased resistance. Scrubbing the electrodes with steel wool works for about a week. Any ideas for a permanent solution?
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This is a common problem in any sensors that deal with moisture (soil moisture sensing or rain detectors or water level meters). Stainless steel probes may work better. I had better luck with non-metallic conductive probes. I use carbon rods from old carbon-zinc batteries. Carbon, most of the time does not react the way metals do and when it does, it does not cause non-conductive oxide layer like metals. If you can find conductive carbon rods, (I hope modern battery cells still have carbon rods) please try them out.
If the sensor is powered with a direct current voltage, you may be out of luck. However, here are some possible 'fixes'.
I read that the phone company, many years ago, had a problem with corrosion and switched from a negative ground to a positive ground, which helped to solve their corrosion problem. If you could insure the system is + grounded, this may help.
I think that most serious outside systems use AC sensors, and if they use DC, employ a positive ground, and are not powered unless a measurement is needed.
