Has anybody ever used the Nature 2 system? At some point every year I have developed a black algae problem which, as most know, is very tough to get rid of. I just bought a Dolphin robotic to hopefully help with some of the scrubbing chores, but thought that adding another defense might help. I have been using the grocery store method for my chemicals, and never have a problem keeping my water crystal clear. Just want to try and keep the black algae from returning!