Another question about our brand new 22mle. our fresh water tank indicator will be red when empty, but the black and grey tanks even when empty (brand new) always have shown 1 green dot. I'm assuming this is normal?

The reason I ask is our first outing was from Friday 3pm to Sunday 11am and our grey water tank indicated full by the last day. Campground lost power which meant no water Saturday Night through leaving Sunday. We took 3 short showers using the off/on feature of the sprayer, I washed dishes 3x (Not a sink full) and we turned the water off when washing hands and yet...still indicated full.

Doesn't seem like we could have used 45 gallons of water in 30 hours.