I need to apply Vitamin C to a stain in the deep end of my pool. I've read where people put it in a sock and weigh a rock down on it, but I can't swim all the way to the very bottom where it is. It is even on the sloped part where a rock wouldn't rest. Any other suggestion for how to rig it in the end of a pole or something so I can hold it there long enough to see if it lightens it?