I have been using Genes fantabulous clay ever since he was kind enough to send it out to anyone who was interested a while back.
I use it every other evening in my pond without fail. My pond is gin clear and the water chemistry is perfect. The koi enjoy swimming thru it as well. Just to make sure that I always put in the same amount I use a digital scale that measures in grams and ounces. I tbls per 1000 gallons.