do I need to adjust TA or CH with these readings?

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NSBFAN

Active member
Nov 13, 2015
43
Minnesota
Hi everyone,

Things have been going well with the pool and this is the first time I've had a situation where I wonder if I should adjust either TA, CH or both. Here are the readings using Taylor K2006:

FC: 9
CC: 0.0
PH: 7.4
TA: 70
CH: 260

water temp is down to 52 degrees F. Using the Taylor SI dial I get a -0.4, so that suggests I need to tweak this up so it is not corrosive.

Should I get the CH up to 270 or more?
 
Hello! Using the Poolmath calculator and the readings you provided, I actually came-up with a CSI of -0.59 which is quite low. A big reason for that is the water temp of 52. That has an amazing effect on your CSI. While your recommended CH level is anywhere from 250-350, increasing CH alone doesn't really get your CSI back to zero (level) very quickly. Allowing your pH and TA to increase a bit does though. For example: Increasing CH alone to 300 changes CSI to -0.54. But if you also increase pH to 7.6 and TA to 90, your CSI goes up to -0.21. Still not perfect, but changes much faster. You may want to adjust those 3 items while watching your water temp over the next couple months. Once temps begin to rise, you won't have to work as hard. Another example: If your water temp was 70 degrees with those example numbers I gave you, the CSI would be "0". :)
 
Many of us never calculate CSI. If you stay within the guidelines we suggest, you will have no problems with that pool where it is.......again, because it is within the guidelines.

If you still decide you need to rely on it, Taylor says
No chemical adjustment is necessary if the SI is within ±0.5 units of zero;
Click to expand...
Next, there is a very good chance the coldest is over in FL so even less reason to be concerned.

In short, I suggest you leave your pool alone.
 
Thanks everyone. Yes I don't expect the water will stay so cold moving forward - at least I hope not! My PH seems to rise pretty regularly and likes to sit around 8 until I add acid, so I'll see what happens there. I think my last acid application was a bit heavy as it went from 8 to 7.4.
 
First of all, I agree with everybody else: "It is the low temps!" If you recalculate your result using 80 degrees, you'll see what a huge difference it makes. (By the time you get to 60 degrees, you'll be fine.) However, I'm going to note that in the absence of a given CYA value, you are possibly exceeding -.50 CSI units..... so, maybe you want to bump up the CH a little. If you are consistently having a pH rise, you may want to consider a lower TA.... which may mean a further adjustment to CH....

Do you always run that much chlorine, when the water is this cold? Or do you really have a CYA of 80-ish?
 
i just found this article in pool and spa news 2011 , link is Manufacturers Require Additional Water Balance Index - Pool & Spa News
. this article may have some bearing on your question.

for the record, i am a newbie to pool chemicals so i am not qualified to make suggestions, i know there are many TFP members who don't believe in using a saturation index, and i never heard of ryznar index before reading the article. but i also didn't know that pool equipment manufacturers may void a warranty because calcium hardness isn't where THEY want it to be.

disclaimer: i am NOT posting this to start an argument or state a position about anything, because i don't have enough knowledge to have a position. i came across this article because i'm trying to learn about pool chemicals just like NSBFAN is.

[h=1]Manufacturers Require Additional Water Balance Index[/h][h=3][/h]By Ben Thomas



  • Different values: The Ryznar Stability Index correlates higher values with more corrosive water, and lower values with water that is potentially scaling. Its value range is also different from that used by the Langelier Saturation Index.
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Different values: The Ryznar Stability Index correlates higher values with more corrosive water, and lower values with water that is potentially scaling. Its value range is also different from that used by the Langelier Saturation Index.








When Cynthia Wilson noticed a persistent leak in a commercial heater she’d been servicing, she did what any pool service technician would do — called the manufacturer to request fulfillment of the warranty. But when the manufacturer’s investigator performed a water analysis, the results caught Wilson off-guard.
“Their evaluation worksheet said that we’d failed to maintain the necessary [calcium hardness] levels for the equipment warranty to cover the damage,” said the vice president of operations at Like New Pool Services Inc. in San Diego.
“Even though our water was balanced according to the Langelier Saturation Index, it was considered corrosive by the Ryznar Stability Index.”
This development would likely have thrown most service people for a loop.
Within the pool industry, the Langelier Index is taught almost exclusively, and many service veterans remain unaware that any other water balance indices even exist. “The Ryznar Index is basically not taught by anybody, except that it’s sometimes briefly mentioned in certified pool operator classes,” said Alison Osinski, Ph.D., president of Aquatic Consulting Services in San Diego.
Nevertheless, several heater manufacturers have advocated or required the use of the Ryznar Stability Index for years. Though these manufacturers also tend to promote the Langelier Saturation Index, some pool chemistry experts say the two indices aren’t always compatible. “These two formulas can conflict,” Osinski said. “They’re looking at the same issues, more or less — but the Ryznar Index wants you to have much higher calcium hardness.”
Representatives of companies that support the Ryznar Index explain that this higher calcium hardness mediates the water’s potentially corrosive effects on metals. “The Ryznar Index is oriented toward protecting equipment’s metallic surfaces, whereas the Langelier Index is focused on protecting the calcium of the pool shell,” said Rich Murphy, national pool sales manager at Lochinvar, a heater manufacturer whose warranty specifies the use of both the Ryznar and Langelier Indices.
While the Langelier Index is geared to prevent either scaling or etching, the Ryznar Index is designed to allow a slight coating of calcium to accumulate on metallic equipment, where it acts as a protective insulator.
But therein may lie the problem. “In Southern California, our water already contains too much calcium,” Osinski said. “That buildup causes all kinds of issues with oversaturation, and it clogs up our pipes, and coats our heater elements, and damages equipment.” Thus, Osinski and others have pointed out, adding additional calcium to bring the water into Ryznar-acceptable balance could lead to excessive calcium scaling in some cases.
This leaves service techs like Wilson feeling caught between a rock and a hard place. For other pool professionals concerned about a situation like this, experts agree the safest bet is to become familiar with the equipment’s warranty paperwork — and if the manufacturer mentions the Ryznar Stability Index, to try to keep the water balanced into the range where both the Langelier and Ryznar indices will consider it to be noncorrosive.
“If you maintain a Langelier Index value of 0.0 to +0.5, you’ll be right in the Ryznar Index’s ideal range,” said Kim Skinner, co-owner of Pool Chlor in Livermore, Calif.






 

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