Let CL level drop to half normal level???

Mendy48

Bronze Supporter
Apr 27, 2018
902
Midland, MI
I know... I know... this is defiantly a dumb question, but I think I did this wrong last year or I'm overthinking it.

For closing, after I perform my OCLT and it passes (which it did), it says to let my CL level drop to half normal level. If my normal/target level is between 4-6, with a CYA of 30, what is half my normal level then?

Why can't I figure this out? :unsure:
 
Last edited:

tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
11,050
Franklin, NC
High levels of chlorine can oxidize PolyQuat (i.e. break it down). So, if you closed at near SLAM levels the FC would quickly drop.
 
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ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
20,474
Northern NJ
I know... I know... this is defiantly a dumb question, but I think I did this wrong last year or I'm overthinking it.

For closing, after I perform my OCLT and it passes (which it did), it says to let my CL level drop to half normal level. If my normal/target level is between 4-6, with a CYA of 30, what is half my normal level then?

Why can't I figure this out? :unsure:
That is not what it says. Closing an In Ground Pool - Trouble Free Pool says:

Two or three days before closing, I bring the pool up to shock level and hold it there until FC holds overnight (which it generally does right off on the first night). Then I let the chlorine level fall about half way back to normal levels, typically another day and a half.

That means from shock level bring FC halfway to your normal level. SLAM level is 12, normal is 4-6, then bring FC around 8 or less.

Having a moderately higher level (say, half-SLAM level so FC/CYA ratio of 20%) is OK, but the idea is that the Polyquat should last through the winter even if the chlorine does not.

Buckman Labs says that the Polyquat that is broken down is still effective as an algaecide. Moderate to high levels of chlorine break down polyquat, but only turn it into shorter chain polymers that are still effective.
 
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Mendy48

Bronze Supporter
Apr 27, 2018
902
Midland, MI
That means from shock level bring FC halfway to your normal level. SLAM level is 12, normal is 4-6, then bring FC around 8 or less.
So half way to my normal level is 8? Not 2-3? I'm really not sure why I can't figure this out or why this is not making sense to me.

Last year, I SLAMed my pool and let it drift down to whatever and didn't pay much attention to it. This year, I'm trying to understand what it means, but can't. Don't get me wrong.... I understand the reasoning behind doing this, but I just don't understand what it is I'm doing. Like..."That means from shock level bring FC halfway to your normal level. SLAM level is 12, normal is 4-6, then bring FC around 8 or less." I don't get this.

?‍♀ I'm just trying to understand. That way, I can explain it to someone or even my husband.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
20,474
Northern NJ
You start with SLAM level of 12. Normal is 4. What is halfway between 12 and 4? 8.

Nothing says to go below a normal FC level.

It really does not matter. Any FC level with Polyquat will be ok.
 
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