Should I shock?


Well-known member
Yesterday I had what I would consider my first "heavy swimload". 9 young kids and 5 adults for a pretty much all day swim event. By the end of the day water was slightly cloudy as I would expect but nothing too bad. Cleared up this morning. I did an over night FC loss test last night and it dropped by about 1.0 to 1.5 ppm overnight. Is this normal given this load or should I shock it? I have yet to shock my pool as I am a new owner (although the PB shocked it when opening it this year).

Part 2 of the question, if I do need to shock I will likely use bags of shock provided by the PB since I have them. I chlorinate with bleach, but since I have the shock bags, seems easier than a bunch of jugs of bleach. Would I just throw this directly into the pool, dump it in a skimmer or what? Also with the bags is it a once and done process or do I still monitor the FC level to keep it at shock level as indicated in Pool School?

Thanks for helping a rookie out,


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
As long as the FC level never went down to zero, and you add some extra chlorine today (FC level perhaps 3 or 4 higher than normal) you won't need to shock. A large swim party puts lots of organic debris (shed skin cells, dirt, etc) into the water, which take a little while for the chlorine to break down.

The pros and cons of using the granular shock depend both on which particular kind you have (dichlor, cal-hypo, trichlor, lithium-hypo) and what your current levels are. Dichlor and trichlor add extra CYA, while cal-hypo adds extra CH. Depending on your current levels, you may or may not want to add those to the pool.