After 5 days away from home, this is what I found. Brownish matter clinging to probes and bottom of reservoir tank. Flowed in the current on the probe. It’s not slimy. Any ideas?
If its not smiley it's most likely a nutrient/mineral buildup. I use regular tap water and get that with general hydroponics. It would usually be white but the nutrients stain the buildup brown.
Happy Growing