I bought this stuff out of curiosity, from Drs. Foster & Smith.
Blue Vail Water Colorant
text from site:
"This super-concentrated blue colorant turns water a sparkling sapphire that's as friendly to animals and fish as it is to the eye! Use one-fourth as much Blue Vail as you would any other dye. We recommend Blue Vail for use in controlled waterways like private ponds, lakes and fountains. Use only one quart per 1,000,000 gallons of pond water. Lasts up to four months. (One quart is equal to one gallon of other brands.) "
They ain't kidding about super concentrated! I just wanted to try it out, so after a cursory glance at the label, (and without calculating or measuring) I poured some in. 1/4 cup or less, for certain. I thought I was being conservative. Then I sat back with a frosty beverage to watch it disperse. It took nearly an hour to fully disperse. Very much to my chagrin, my pond is now the darkest blue you can imagine! you cannot see more than 4 inches deep anywhere, it's so blue. It looks like it's ready to dip Easter eggs in it to dye them!!!
I need someone to protect me from myself! How dumb can I be? Gonna take a good bit to top this one, even for me.
Now I have to change a lot of water, which I hate doing in the pond (it tends to lead to algae outbreaks), but if I don't, I think my submerged plants will die from lack of light. I will say this though, it really is non-toxic dye, all fish, frogs, and plants are fine. Although the frog seems to have become a bit blue-ish, which embarrasses me to no end.
If/wehn I try it again, it will go in at a rate of 5 drops at a time.