This is awesome stuff! Dont see how I was spraying without it. Now can see what the heck I'm doing. I use about 3 ounces for 3 gallons of spray, and it is plenty. Seems to take about 2 days to vanish, more if in an area sheltered by trees or something. Since I really have to localize what and where I spray, this provides great knowledge.

I was really nervous about some of the bad reviews on here... This product did exactly what I wanted it to do amazing. I will definitely buy again, and for the people complaining about it staining things they should probably be paying a someone else to work on their yard

Well .. it's blue!

I wanted to spray Prodiamine (Barricade) by myself this year in my lawn, and I wanted a blue marking agent to feel more confident that I was covering all areas and not overspraying. My equipment was a Field King Professional Backpack Sprayer.

After some minor testing with JUST WATER, I could easily see where I had sprayed with HALF the recommended dosage of blue concentrate. I had read other reviews warning that Prodiamine is yellow and mixing with blue will obviously result in a green mixture, so some people recommended even more blue than recommended for it to stand out. However, once mixed with Prodiamine, I found that if I used JUST OVER HALF the recommended dosage of blue was easy enough to see most of the time. I struggled to see it all of the time. Next time, I may go closer to 2/3 dosage. Also note that I didn't have a full green yard yet, so that may also be why I was able to see it better. Maybe I would have to up the dosage more on a really green yard.

I was nervous the blue would stay for many days after using. I basically watered in the Prodiamine the same day, left town for the night, and I couldn't see any blue when I returned the next day.

Overall, this product does what it's intended to do. Five stars.

WHAT I WISH I DID DIFFERENTLY:
1. After carefully pouring the blue from the concentrate container into my measuring cup (old baby bottle) and replacing the cap on the container, I wish I would have realized that some blue concentrate was still under the cap. When I put the bottle back in my garage, it dripped from under the cap and my garage floor is stained blue. I recommend washing the outside of the bottle after using (especially getting into the cap crevice if you can) to limit the concentrated drippage, and definitely store the concentrate container within a larger plastic container of some sort.
2. After spraying my yard, I carried my backpack sprayer into the garage and set it down. My backpack doesn't leak, but my backpack was still pressurized. I bumped the trigger an hour later while moving some things around, and it sprayed some blue ... staining my floor in another spot. I wish I would have at least depressurized the backpack before bringing into the garage. Even better would have been to take care of the residual mixed solution in the backpack before ever bringing it into my garage.

I used about 2 ounces per 15 gallons to spray for duckweed on my pond. With the dye it was easy to see where I had sprayed. It will stain your hands if you don't use gloves, but most of the stains come off easily with a couple of washings. I also stained the pants I was wearing and those stains came out in normal washing.

As far as marker, this stuff marks well, and a little goes quite far. My suggestion to the company would be a better storage container. This will leak and get everywhere. I placed bottle in a zip lock freezer bag, and a lot of dye found its way out of the bottle some how. I would suggest a leak proof top with a smaller pouring hole. I poured all the dye into a large Dawn dish soap bottle and it worked great. No leaks and was much easier to control the pour.