How much UV dye to add to water?

Has anyone used UV dye at all, if so, how much did you use? Does the 'glow' increase-the more you add?

I'm using leak detector for radiators, so it may be a little different... but I keep putting dye in a few drops at a time until i like the look. The more dye I add, the less traspartent it gets, and the brighter (but darker colored green) glow there is. If I add a little bit, it glows more yellowy, if i add more dye it glows purpleish green. On the bottle it says 0.3% Fluorescent dye, and i'm guessing I using about 20-30 drops. Oh, one more thing... the stuff I have tends to soak up UV light so that the side of the tubing that is oposite of the UV lamp glows slightly less brightly.

It's personal preference how much to add... just experiment.

cool, I will try it out as soon as my UV lights get here.
thanks