How to tell when your blue boy is full

[Riwright]

Found this method on another board, thought it was worth repeating.

Get one of those short lengths of clear sewer pipe that lets you see the water as it flows through the sewer hose. Attach it directly to the blue boy. Attach the sewer hose to the clear pipe. Raise the top of the blue boy (the part furthest from the sewer opening) a few inches.

Open the black valve and let the black water flow until you see a little standing water in the clear pipe. This means the blue boy is almost full.

Remove the block and lay the blue boy flat. Open the gray valve and rinse out the hose just a little.

Your blue boy is now perfectly filled.