Originally Posted by MargiLou
I bought a used 2008 Forester. During the "walk through", my husband and I were shown the release valves for the grey and black water tanks. It was not until stagnant water that smelled like a dead animal backed up into the shower that we were aware of the galley tank being a second grey water tank. None of the info we received lists the capacity of the galley tank, so we are always emptying to avoid that stinking situation again. Needless to say, the Convenience Center monitors are mostly incorrect. Even immediately after emptying, a couple of them never return to "E" and Black never shows less than two thirds.
Is there a way to find out the capacity of the galley tank?
You should be able to find capacities online. Usually, both galley and bath have the same capacity.
There are various methods to clean your tanks. Usually it is not needed to this extent but for your black tank ~~ I would get a commercial black cleaner called Commando, add 1 cup of Dawn dish liquid, and 15 gallons of water ~~ go for a 25 mile ride and let it slosh. Take that ride to a dealer and buy a tank flush wand.
The gray tanks are easier... pour a 1/2 gallon of bleach down each one ~~~ NOT your FW tank. Add a cup of Dawn and 5 - 10 gallon of water and take that ride.
Your gray tanks should not need much after that. Your black will need cleaned due to solids and paper. Some use household products in what is called the GEO method. I've been using chemicals for 42 years and not about to change.
Tank gauges are notorious for being inaccurate. It is possible to have new sensors put in but they are generally the same. It may take a couple cleanings for you black tank as there is probably something that stuck and dried on the sensors. My last 3 have had pretty accurate sensors from the factory and remained that way be taking care.