Quote Originally Posted by famousdavis View Post


I got the idea that you shock a pool on a regular basis because the Pinch-a-Penny test results print-out says that that's one of the ABC's for a healthy pool -- you shock it once a week.
Yep, and they can sell shock that way on a regular basis. Works better for those that don't have salt pools but you get the idea. Pool stores are in the business of selling chems and things like shocking weekly and pushing phosphate removes (and selling "mineral systems") hellp increase their bottom line. Shocking once a week is really one of the ABCs of a healthy pool STORE since it increases their sales.

I'm intrigued that you and others don't do this, yet don't have troubles with your pool. I thought that over time the combined chlorine becomes a problem, so shocking weekly pretty much elminates any CC you have in the water? If you only shock when the CC reaches some threshold, what is that threshold?
If you have CC over .5 ppm then shock. If you keep the FC in line with the CYA level by keeping it at 5% of the CYA in a salt pool or following the Best Guess Chart (that I linked to above) then the fact of the matter is that you will basically not have CC. If you try and run your FC lower than this you will and will need to shock. Period. The correct FC for the CYA will keep einough 'active' chlorine in the water. Also, in a salt pool the water in the cell is being 'supershocked' to very high chlorine levels when the cell is on.

Trivia: for most people the 'threshold' where their nose can detect CC is .4 ppm.