I got a block tester to check my head gasket.

Anyone have experience using one?

I did read the directions.

The fluid was very pale blue, I thought typically they were a darker blue?

I filled it to the fill line, let the car warm up to operating temp and then inserted the rubber piece into the radiator neck as the car was running and pumped to 2 minutes, I did see the the fluid move as I pumped with some bubbles, so I guess it was working?

The fluid never changed colors, no yellow, so I guess I am alright?

Are you supposed to keep the car running as you pump?

Here is a pic of the fluid, very pale blue I thought should be darker blue?