@ Chem_Geek

I've used monochloramine . . . and it works. But it's VERY irritating to swim in. In commercial pools, pre-season, 2 ppm got complaints from the guards and 5+ ppm ran them out of the pool with itchy red skin in minutes. Plus there seemed to be some sort of 're-bound' effect: the algae would clear, I'd achieve a CC< 0.5 ppm level, and then algae would return. It happened a couple of times, and I swore off the stuff, except for cleaning swamps.

I was focused on the outcome, and not on investigating what was happening, so I don't doubt that there may have been confounding factors. But it's left me very reluctant to recommend that approach.

I can testify it *does* result in a fast algae kill, and monochlor *will* penetrate sludge layers, rather than just oxidizing the top, like FC does.

It's fair to say, more research is needed. But I haven't had the opportunity.