detergent is to break water surface tension & to help it flow out
(as opposed to form beads)
it's too much if it 'suds up' when you stir!
:-)
for fun surface tension experiment:
put water in small glass, sprinkle black pepper on surface.
(it should float)
wipe your finger across the top of the detergent bottle
(if yours has a glob of soap on it)
touch your finger to the water.
THAT'S what the detergeant does.
:-)