So, am I ready to ROCK???

[chem geek]

From my understanding the biggest problem with superchlorinating with the cell is not the shortening of the cell life (although that IS a concern) but that the FC levels rise slowly over the period and during this certain types of complex chloramines can form when FC levels are high but below breakpoint that make it more difficult to reach breakpoint than if the proper amount of chlorine is added all at once to reach a desired ppm of FC. (Richard or anyone else please correct me if I am wrong on this, my research indicates this is true).

I don't have a salt cell, but even at full power and running 24/7 you are right that the increase in chlorine levels attained in the pool will be much slower than dumping liquid chlorine into the pool. However, if one is starting from an existing free chlorine level then whatever chloramines that would have been formed have already done so. Free chlorine combines with ammonia very, very quickly to form chloramines. It is the next steps to breakpoint that are slow (and free chlorine oxidizing organics can also be slow). So from a chemistry point of view, I don't think the slow increase in FC from a salt cell would be an issue unless the FC were at or near zero for some reason -- perhaps if there were a major ammonia (i.e. urine) accident that overwhelmed much of the free chlorine in the pool, remembering that you need about 10 times as much FC to achieve breakpoint as there is ammonia.

Urine is about 2.5% urea by weight and urea is about 50% nitrogen (ammonia) so 2 cups of urine produces around 5 grams of ammonia and that requires about 50 grams of chlorine for breakpoint. A 10,000 gallon pool is about 38,000 liters fo 50 grams of chlorine in 38,000 liters is 1.3 ppm. So depending on size of pool, FC level, and size and number of accidents, one could use up all the FC in a pool. And certainly one uses up the FC in a local area rather quickly.

So if you need to superchlorinate because of an "accident", then I agree that quickly administering a large dose of chlorine is wise so that breakpoint is more easily achieved. If instead it's just a small amount of measured combined chlorine that has accumulated, possibly from slow combining with organics (not ammonia), then a slow rise in chlorine would probably be fine. Of course, the issue of the life of the salt cell is real and adding liquid chlorine is easy and relatively inexpensive.

[EDIT] In the presence of CYA, the breakpoint chlorination process is slowed down considerably since CYA reduces the disinfecting chlorine concentration. A normal breakpoint at an FC of 2.0 ppm with no CYA takes around 30 minutes to effectively complete so with 30 ppm CYA this would take about 11 hours if there was no sunlight. I don't know how much faster breakpoint goes with sunlight. [END-EDIT]

Richard