I'm new to Arduino and still learning the basics. I tried reading water level by using this sensor I left it in the water for about 5 minutes then I noticed it changing color (some parts darker than other)like the water is still over it . So my question is do Water sensors really rust ? or is it my own imagination?
The color change you observed is probably caused a galvanic reaction between metals in the sensor and other metals that are present, such as the tank, piping, or dissolved metals in the water. Do not modify the parallel strips of metal on the sensor. This will render the sensor useless. To reduce the effects of galvanic corrosion, you can: 1) Reduce the current passing through the sensor. To do this, sample the sensor less frequently. For, example, sample it once every second. 2) If possible, remove sources of metal from the water. For example, replace metal pipes with PVC, and replace screws with plastic zip-ties. 3) Move the sensor further away from sources of metal. 4) Place a grounded sacrificial zinc in the water, close any other metal sources. If the water is circulating, place the zinc near the inflow opening. 5) Remove stray or electrical currents from the water. Connect the "-" pin (GND) and the water to the same ground.
I have that same sensor, and found a couple things to help with this issue. The first thing that I did with min was tin the contacts with solder (All 10 'sensor contacts' all the way down) and also, using the GPIO, only power it on about 1 second before I read it, and turn it off immediately after. By reducing the amount of time current is running through it, you reduce the tarnish, and the solder i tined everything with is less likely to corrode than the raw contacts.