Quote Originally Posted by waterbear
Perhaps the boron is killing some of the nasties in the water so the chlorine doesn't have to?
Yes, but how many nasties are there in water each day? The largest consumption of chlorine by far is the breakdown from sunlight as this generally consumes about half of whatever ppm rate you maintain with your SWG system. So, at 4 ppm this would be 2 ppm lost by breakdown from sunlight.

What we don't know is how much your SWG additionally produces and is consumed by bugs or is used to oxidize organics or ammonia. This could be any amount, but I'm guessing that it is far less than the 2 ppm consumed by sunlight. Generally, the next large consumer of chlorine is ammonia or its biological organic equivalent urea found in sweat (which is mostly water and salt) and urine. Finally, chlorine is consumed by other organics (mostly by nitrogenous organics) from various sources (suntan lotion, material blown into the pool, etc.) but is a rather slow and inefficient process.

Richard