[rohrmann]

Our black tank valve pull was always difficult to open and close. I started using 4 oz of Thetford valve lube, along with a capfull of liquid Calgon and for a long time, 4 oz of Power Blue tank treatment. This helped, but they were still pretty tight. Last year I started using TankTechsRV in the black tank, and the black valve has gotten much easier to pull and close. Don't know if I've gotten stronger, but the valve moves better. I normally don't use anything in the grey tanks, so they are firm, but have never been real hard to operate.