SWGs and cold spats

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renesme

renesme

Gold Supporter
Jul 5, 2018
143
Katy, TX
Pool Size
9100
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Under normal conditions our SWG is set to 40% and the pump runs from 8 AM to 5 PM. This keeps us at a steady daily FC of 7. During the recent cold snap I left the pumps running basically 24 hr/day which caused the FC to spike to 13 before the water got too cold. Should I have bumped the percentage on the SWG back a bit in anticipation of the longer pump time? Or does it really not matter?
 
Yes, when you increase your pump runtime you need to lower your SWG % to maintain a stable FC level.

No harm with a FC of 13 but at some point you need to let it drift back down.

Note that your pH test is invalid with FC above 10. So don’t do pH adjustments until your FC is lower.
 
ajw22 said:
No harm with a FC of 13…….
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I’ve always gone on that assumption, I have normally been using 8-12 as my ’safe’ range. Lately I’ve been wondering if the FC levels at the high end of that range might be more likely to encourage iron staining, if there is any iron in the water. Is that true?
 
revitup said:
I’ve always gone on that assumption, I have normally been using 8-12 as my ’safe’ range. Lately I’ve been wondering if the FC levels at the high end of that range might be more likely to encourage iron staining, if there is any iron in the water. Is that true?
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Not directly. High pH can cause iron to precipitate out of water. Adding a large dose of liquid chlorine can temporarily cause pH to rise. So it is not the FC level and will not happen from a SWG raising FC slowly.
 
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ajw22 said:
Not directly. High pH can cause iron to precipitate out of water. Adding a large dose of liquid chlorine can temporarily cause pH to rise. So it is not the FC level and will not happen from a SWG raising FC slowly.
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Not to steal this thread and I’m sorry, but by high PH, are we talking high 7s? Or higher?
 
revitup said:
Not to steal this thread and I’m sorry, but by high PH, are we talking high 7s? Or higher?
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All depends on the level of iron saturation. It is more a sudden large pH rise then any specific level.
 
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