When a pool service company closes the pool, they add their chemicals right then, without circulating them. I intend to shock (with bleach) and filter my pool the night before they come. At that point, they'll need to get into the pool to take out the ladder, stick their arms in the water to put on the aquador and such...is it safe for them at that shock level? My CYA is 50, so I've kept my FC at 4, and will shock to 20....thanks.

Pretty much anything over 10 ppm is not recommended, but if they are only in for maintenance and limiting there exposure it might be ok. How long will the procedure take??

Sal...did you mean 20ppm vs 10? FC of 20 would be shock level with CYA at 50

dmanb2b, I think she wants to know what level is ok to swim in?? 10 ppm or higher is not recommended right??

No, not really. You can swim in FC up to shock level for the CYA in the pool. For 50 ppm CYA, its ok up to 20 ppm.

I stand corrected!!!

At usual shock level where the FC is around 40% of the CYA level, this has the same active chlorine (hypochlorous acid) concentration as a pool with 0.6 ppm FC and no CYA (or possibly 1.2 ppm FC with no CYA at 90ºF) which is lower than found in most indoor pools with no CYA. This is not unsafe, but it will likely oxidize swimsuits, skin and hair more rapidly and certainly one should avoid drinking large quantities of pool water (not something one normally does anyway). You basically will experience more of the annoying aspects of typical commercial/public indoor pools except it shouldn't smell as bad since the bather load is so much lower and it's outside in the sun with better air circulation.

Thanks ChemGeek and everyone else who replied...I thought that was the case, but I feel better having it confirmed!