If that's is algae it's been killed, because living algae will be a whitesh color. If the car is like 123 cars you will need to pull the fuel strainer out of the bottom of the tank as it may need cleaning also.

__________________
'10 Chrysler T&C Stow-N-Go White. Grandpa's ride.

'13 Chrysler 200 Touring Candy Red. Grandma's ride.

Age and cunning will always over come youth and vigor.