The higher Cl level has been developed from heuristic methods by Ben. It's what "works" out in the field. Cl has been scientifically proven to be less effective at higher CYA levels. My other reason for keeping a higher that 1 Cl level is that it gives you some sanitation "reserve" in certain circumstances. I'd prefer to keep it at 3 and give myself some wiggle room, than to be bumping along the lower limit at 1.

However!

If it ain't broke, by all means, don't fix it!

Michael