Water temperature vs growth

cj133

Well-known member
May 6, 2018
506
NJ
With winter approaching in my area it has me wondering a few things that I haven't been able to find.

Is there a chart anywhere showing how fast things grow vs water temperature?
Does required chlorine PPM drop or does consumption drop with water temperature?

At what water temperature is chlorine no longer required to stop things from growing? I'm asking this simply out of curiosity for when the best time to close and open my pool is.

I realize I'm putting way too much thought into this but my mind wanders sometimes and questions like this come up.
 

PointeTaken

Bronze Supporter
Aug 28, 2019
143
Hoover, AL
Pool Size
12000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Hayward Turbo Cell (T-CELL-5)
Typically once your water temp drops below 60 degrees F algae growth will be virtually nonexistent. If you really want to get into the science of the sanitation levels needed for a given temp, @chem geek may have a detailed answer for you.
 

Chickinvic

Well-known member
Jul 12, 2017
264
Ottawa, Ontario, Canada
Since our heater and salt cell both crapped out earlier this month (Murphy's Law), I have been manually adding liquid chlorine. But, I've barely had to add much at all. The water temperature is currently in the upper 60s. Hopefully the new heater will be in next week.
 

ajw22

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TFP Guide
Jul 21, 2013
29,718
Northern NJ
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Pentair Intellichlor IC-60
Does required chlorine PPM drop or does consumption drop with water temperature?

 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,718
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Is there a chart anywhere showing how fast things grow vs water temperature?

Figure 3 in https://aem.asm.org/content/aem/36/4/572.full.pdf

 

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PointeTaken

Bronze Supporter
Aug 28, 2019
143
Hoover, AL
Pool Size
12000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Hayward Turbo Cell (T-CELL-5)
If i recall correctly, the tilting of the earth away from the sun (in the northern hemisphere) causes the lower rays and temperatures. It also inhibits everything else from growing as well.

And just how high or low that angle can be at any given time of year depends on your latitude. Anyone between 23.5N (the Tropic of Cancer) and 23.5S (the Tropic of Capricorn) can see maximum sun angle reach 90 degrees. At the summer solstice, the sun is at 90 degrees over the tropic of cancer. At the winter solstice it is over the Tropic of Capricorn. During the two equinoxes, the sun is at 90 degrees over the equator. At either equinox, if you subtract your latitude from 90, that’s the highest the sun can be at that time. At summer solstice, you take your latitude, subtract 23.5, and then subtract that difference from 90 to find the noon sun. If you’re in Minneapolis at 45 degrees north latitude, the highest you’ll ever see the sun is 68.5 degrees above the horizon. Here in Alabama at 33.5N, the highest we see the sun is around 80 degrees, hence the much hotter summers. For winter you do the opposite to find the noon sun angle. Add 23.5 to your latitude and subtract from 90. So here in Alabama we see a max sun angle of about 33 degrees midday on December 21. In Minneapolis, the sun doesn’t get above 21.5 degrees above the horizon at winter solstice, hence colder winters.

Here is a fun but powerful little tool to play around with: Calculation of sun’s position in the sky for each location on the earth at any time of day [en]
 
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