Hi Doken
Congrats on your new camper and welcome to Sunline Owners Club
Gray tank sensors, yes they can get scum on them inside and then make a connection and give a false reading.
I would not take the sensors out to clean as only a last, last resort. Odds are in your favor the entire tanks is scummed up.
The 1st simple thing to do is use it!. There is no harm to the camper not reading right. It might and might not go away on it's own.
If it needs help, try this product.
Happy Camper - Odorless Holding Tank Treatment Black and Grey Water
Look for the extreme clean product. You put some in the tank, (mix in water and pour down drain,) then fill the tank with water until it comes up in the shower. This cleans the top of the tank too. Let it sit overnight or longer and then drain and rinse. It will naturally eat off the scum. You can even do this at the camp ground the day beofre you head to the dump station.
There are other products out there that clean sensors but this one works with my septic system at home. I also use it in the house to clean out slow running drains
Hope this helps
John
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Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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