Slaming before closing the pool

[RESISTENCIA13]

I read an announcement about closing the pool. It mentioned to slam 2-3 days before closing. It also stated that FC level will return to normal within a few days. I do not understand how the FC can drop to fast. What type of shock can drop the FC so fast? I ask because in my case normal FC is 6 PPM and shock level is 28 PPM. I cannot see how it will drop from 28 PPM to 6 PPM in a few days specially at closing time with the low temperature.

 

[jblizzle]

All the announcement does is point you to the articles in Pool School.
The article also does not say to let the FC drop back to normal levels. It says that it will drop half way to normal levels in a couple days and that is when you close.
There is not "type of shock" ... regardless of what form of chlorine you use to raise the FC level (obviously liquid is the best), it will still drop at the same rate due to the losses to the sun.

In any case, it really does not matter how fast it drops, the idea is to close when the water is cold and your have a decent FC level left so that when you open in the spring there is still FC available.

 

[RESISTENCIA13]

So it's ok to close with FC levels of 14PPM or higher?

All the announcement does is point you to the articles in Pool School.
The article also does not say to let the FC drop back to normal levels. It says that it will drop half way to normal levels in a couple days and that is when you close.
There is not "type of shock" ... regardless of what form of chlorine you use to raise the FC level (obviously liquid is the best), it will still drop at the same rate due to the losses to the sun.

In any case, it really does not matter how fast it drops, the idea is to close when the water is cold and your have a decent FC level left so that when you open in the spring there is still FC available.

 

[Texas Splash]

It is safe if your CYA is commensurate with that FC as listed on the Pool School - Chlorine / CYA Chart. Since your SLAM/Shock level is 28, you really have two choices: If you don't use Polyquat 60, raise FC to 28 and mix for 24 hours then simply close/cover - done. OR ... If you chose to use Polyquat, raise FC to 28 for 24 hours, then allow FC to fall to 14 before adding the Poly. Depending on the amount of sun you receive, it may take 2-3 days for the FC to drop. But it will be safe for your pool because your CYA (I'm assuming) is 70. Remember the raise in FC prior to closing is not a true SLAM in the sense of everything you do on the SLAM page (passing the 3 criteria, etc), it's just a precautionary measure to ensure organics (if any) are eliminated before closure. Hope that helps.

 

[RESISTENCIA13]

Thanks.

It is safe if your CYA is commensurate with that FC as listed on the Pool School - Chlorine / CYA Chart. Since your SLAM/Shock level is 28, you really have two choices: If you don't use Polyquat 60, raise FC to 28 and mix for 24 hours then simply close/cover - done. OR ... If you chose to use Polyquat, raise FC to 28 for 24 hours, then allow FC to fall to 14 before adding the Poly. Depending on the amount of sun you receive, it may take 2-3 days for the FC to drop. But it will be safe for your pool because your CYA (I'm assuming) is 70. Remember the raise in FC prior to closing is not a true SLAM in the sense of everything you do on the SLAM page (passing the 3 criteria, etc), it's just a precautionary measure to ensure organics (if any) are eliminated before closure. Hope that helps.