I have been trying to dose my pond with PP. The problem is I have hard water and it is taking a lot more pp than I see recommended and I am worried about over dosing. I dosed 4ppm several days in a row, and the water stayed pink less than an hour.
I did a test with the pond water and determined that 7.5ppm was necessary to keep the water pink for several hours. I administered that today, yet only got an hour or so of pink water. I am worried going any higher could be harmful to my Koi. Any suggestions? Does the hardness of the water affect the dosage that much? At this point, there is little if any organic matter left, so that isn't the issue.