Galley tank

I have a 2010 29RLBS with the 3 tank levers behind the door. I have been consistent in emptying them when we leave our seasonal site after a long weekend or week. My galley indicator light shows 3/4 full. I have pulled all 3 each time, 1st the black, then the two grey levers.

The light has shown 3/4 full the last two times I've emptied them. Again today, emptied all 3 and it still shows 3/4 full on the galley light. Any ideas?

If you are just pulling the levers and letting them drain without any flushing or trailer movement (assume you leave it on the seasonal site), I would assume the indicator contacts are dirty. Not a big problem if you do nothing. Could fill and flush the tanks with water and some cleanser and see if that doesn't help. Can do this easily with the black water and the black water flush valve.

Our blackwater indicator always says full. No matter what. As I've said else where on this site, we have another 5th-wheel, different make/year which always tells us the graywater is 2/3's full. No matter what. Basically I run a calendar in my mind and dump when I think they need it. I can't tell whether or not you park for the season, or tow to/fro. Our two 5th-wheels are parked. The one in Arizona never moves, the one up here travels to in the spring and back in the fall. Again, I dump every so often. I never leave the valves open even though they're almost permanently hooked up to sewer service, well one is at least.

I have used Dawn dish washing liquid in my grey tanks.One of the best and safest grease cutters out there.Fill the tank half full and wash some Dawn down the drain.You have to pull the camper around a little to slosh it around,Then rinse it with vinegar and water.
I have also heard This works too.

My galley indicator does the same thing. When I pull up to a site I pull the grey and galley lever and leave it open the whole weekend and it stills says 3/4 full.