Quote Originally Posted by aratti View Post
Detecting water level with optical system has one big enemy : The algas growth!

Al.
Hi Al,
I was pretty sure You would mention that one, and prepared for it
Illuminate the tube only while checking level. A 2000 liter tank level is not likely to change very much in an hour, so check intervals do not need to occur too often, still EVENTUALLY algae is likely to occur. Perhaps make the sensor rods screw in for cleaning. Dave's UV light would work, but is expensive.