Chicago water report

[crimson avenger]

Can anyone help me with a question regarding the report on the water that is being used to fill my pool today (pool is being set and back filled today). The link is the city of Chicago water report. I also attached the last two pages to the post (12/2019 water report)

https://www.chicago.gov/content/dam/city/depts/water/WaterQltyResultsNRpts/ccReports/CCA-2019-1-4.pdf

Seems like Calcium Carbonate is 135 mg/L which I believe is hard.

I am awaiting arrival of my TF100kit.
Anything I should be thinking of/doing (with regard to calcium... or any other parameters)?

Thanks,

Mark

 

[JoyfulNoise]

Your total hardness, or general hardness (GH = calcium hardness + magnesium hardness), is 137ppm [CaCO3] (you say that the following way in your head - "total hardness is 137 parts per million standardized in units of calcium carbonate concentration"). You calcium hardness is being reported in units of calcium ions [Ca2+] as 35.4ppm [Ca] BUT your TF-100 test kit reports is standardized against units of [CaCO3] so the fill water in that report has a CH of 88.4ppm [CaCO3] when you convert units (that is, 35.4 x (100.1/40.1) = 88.4). The magnesium hardness is reported in units of magnesium concentration which is 11.9ppm [Mg] but when you convert that to units of [CaCO3], it's 49ppm.

88.4ppm [CaCO3] + 49ppm [CaCO3] = 137.4ppm [CaCO3] (Total hardness)

 

[crimson avenger]

Matt, thank you so much for the detailed explanation. Much appreciated.

 

[JoyfulNoise]

Just so you know, your water supplier is adding a good deal of phosphates to your supply water, about 500ppb or so. It’s likely fir corrosion prevention. Your pool water will reflect this value and possibly go higher as fill water is added to make up for evaporation loss. Phosphates are a nutrient for algae growth and so you will want to keep an good eye on your FC to make sure it doesn’t drop below minimums. One could treat water to remove phosphates but that doesn’t make much sense if your source water is constantly adding it back in.

 

[crimson avenger]

Thanks Matt, so if I understand you correctly, I’ll just watch to make sure the algae don’t get a chance to bloom with those phosphates, the best way to do that is to make sure FC is good. Thanks!