Thank you for your reply.
My apologies I made an error in the last posts HOCL % should be read as HOCL ppm.
Does this mean that the calculations in the "PoolEquations" spreadsheet are incorrect?
Using the numbers you mentioned above it seems that the HOCL ppm comes out in orange as 0.021, and the CSI comes out also in orange as 0.46. Orange I believe is cautionary, in that the HOCL ppm is too low, and the CSI is too high which is potentially damaging to the plaster. Please excuse me if I am reading these numbers incorrectly.
Here are the "PoolEquations" numbers.
Measured pH 7.7
Total Alkalinity (ppm CaCO3) 60
Free Chlorine (ppm Cl2) 4.0
Cyanuric Acid (ppm CYA) 70
Calcium Hardness (ppm CaCO3) 350
Total Dissolved Solids (ppm) 3,913
Total Sulfate (ppm SO42-) 0
Total Borate (ppm Boron) 50.0
Total Ammonia (ppm Nitrogen) 0.0
U.S. Gallons 10,000
Temperature (oF) 83
Total Chloride (ppm NaCl) 3500
Carbonate Alkalinity (ppm CaCO3)25.9
Langelier Saturation Index (LSI)-0.33 (shows as red danger too high)
% HOCl (vs. Total Free Chlorine)0.5%
OCl- (as ppm Cl2) 0.042
HOCl (as ppm Cl2) 0.021 (shows as orange cautionary too low)
Calcite Saturation Level (CSL) 0.35
Calcite Saturation Index (CSI) -0.46 (shows as orange cautionary too low)
If one uses the numbers that I calculated then the numbers come out within range and show no cautionary orange but a good green:
Measured pH 7.5
Total Alkalinity (ppm CaCO3) 80
Free Chlorine (ppm Cl2) 6.0
Cyanuric Acid (ppm CYA) 35
Calcium Hardness (ppm CaCO3) 425
Total Dissolved Solids (ppm) 3,933
Total Sulfate (ppm SO42-) 0
Total Borate (ppm Boron) 50.0
Total Ammonia (ppm Nitrogen) 0.0
U.S. Gallons 10,000
Temperature (oF) 83
Total Chloride (ppm NaCl) 3501
Carbonate Alkalinity (ppm CaCO3)61.8
Langelier Saturation Index (LSI)-0.07
% HOCl (vs. Total Free Chlorine)1.3%
OCl- (as ppm Cl2) 0.100
HOCl (as ppm Cl2) 0.080
Calcite Saturation Level (CSL) 0.63
Calcite Saturation Index (CSI) -0.20
If one changes my CYA number only, which you state has no effect on the HOCL relationships, then the numbers look like this. It clearly shows a relationship. Either the spreadsheet is wrong and needs to be modified or your statment might be incorrect. I wish Richard would clear this up for us.
Here are the numbers with CyA adjusted:
Measured pH 7.5
Total Alkalinity (ppm CaCO3) 80
Free Chlorine (ppm Cl2) 6.0
Cyanuric Acid (ppm CYA) 70
Calcium Hardness (ppm CaCO3) 425
Total Dissolved Solids (ppm) 3,933
Total Sulfate (ppm SO42-) 0
Total Borate (ppm Boron) 50.0
Total Ammonia (ppm Nitrogen) 0.0
U.S. Gallons 10,000
Temperature (oF) 83
Total Chloride (ppm NaCl) 3481
Carbonate Alkalinity (ppm CaCO3)50.4
Langelier Saturation Index (LSI)-0.15
% HOCl (vs. Total Free Chlorine)0.6%
OCl- (as ppm Cl2) 0.044
HOCl (as ppm Cl2) 0.035 (reads cautionary orange i.e. too low)
Calcite Saturation Level (CSL) 0.51
Calcite Saturation Index (CSI) -0.29
Even though it seems from some real live experiences of some, but not all, members of this forum (although not proven) that the CYA protects deeper levels the FC is still too low in relation to the HOCL ppm when calculated. My pool is ranges from 4 ft to 4 1/2 ft deep so depth is not an issue for me.
I would agree as I stated above that ORP complicates the issue as it seems to me that, once set, it only stops the further production of chlorine. Although that is a benefit. And I agree, as stated in my previous post there seems little relationship between ORP and FC. "NO" relationship I am not sure I could not be that definitive as I am neither a chemist, physics major, nor biochemist.
As regards Hawaii and Arizona I think there is difference, we are very close to the ocean, in my case just 1 1/2 miles, Arizona is far. Hawaii is humid most of the time Arizona is dry most of the time, although I have been there when it was very humid. In Hawaii mold grows even on the sidewalks, in Arizona I believe this is not so. Sea going algae must be carried in by the winds here, normally 16 mph to 24 mph. It is unlikely that sea going algae blows into Arizona from the Pacific, although a little might make it.
The black algae here seems to be of a more virulent strain than that which grows in most parts of the mainland.
From my real life experience and that of my friend a FC of 4, pH of 7.6 or above, and a CyA of 70 guarantees one black algae at least where we live, especially in our old plaster pools.
At the present time I think we both beg to differ with each other. As I wrote above it would be good if chem geek could step in and discuss the spreadsheet as this seems to be the area where we disagree. It is entirely possible that it cannot allow for the effect of CyA in a salt water system. If this is so maybe a separate spreadsheet need to be written for salt water pools.
Please bear in mind my pool is 12 years old and while it has virtually no de-lamination it is old, my friends is severly de-laminated and is 17 years old.
At present I will stick with my system as it works for me in Hawaii.
It is entirely possible that we are both right, in our own ways.
One question I do have is, do you not like the pool setup numbers I use, they do not seem to be detrimental in any way? They are admittedly very cautionary.
Lastly as this is getting technical the moderator might wish to move us to the "China Shop". That would be fine by me but it is up to the moderator.
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