PH level and water heaters

summertimesadness

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Aug 23, 2022
73
New Jersey
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Vinyl
I currently have a high CYA of around 100.

I'm keeping the FC level above 10, to keep away the algae issues. Knowing a FC over 10 goofs up PH levels, I'm concerned a bit over using the pool heater at a possible higher PH level.

The pool inspector advised me higher PH levels can damage pool heater (coils?) and to monitor it when using it.

Any thoughts or am I worried about something I shouldn't be?
 
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Charlie Bezzina

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Jul 10, 2021
171
Sydney Australia
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My situation is similar so I am very interested...

How will the heater (and any other equipment for that matter) be affected having fc consistently above the 'recommended' range, and mostly just below the 'slam' level?
 

ferretbone

In The Industry
May 24, 2016
216
tx
If you use the heater or not, the water is running through it, unless you have it bypassed. The magic Ph number for heaters is 7.4....... Any rep from any manufacturer, Will tell you 7.2 to 7.6, sometimes up to 7.8
In the short term go on the high side of Ph if you have to. Because it does not take more than a few days, weeks, months on the lower Ph side to eat away at the copper heating element. Then it leaks. Stains plaster. etc
 

mgtfp

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If your FC is just slightly above 10, the pH test usually still works if you take the reading fast enough. If it is red straight away, then pH is likely really high, if it still starts yellowish/orange and then turns red, the initial reading counts.

You can make a 50:50 dilution of your pool water sample with distilled water (not tap water) and use that to test pH. Because pool water is buffered (it has a sufficiently high TA) and distilled water is unbuffered, the pH of the water sample stays more or less unchanged by this, but the FC gets halved and doesn't interfere with the pH test anymore.
 
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summertimesadness

Well-known member
Aug 23, 2022
73
New Jersey
Pool Size
30000
Surface
Vinyl
If your FC is just slightly above 10, the pH test usually still works if you take the reading fast enough. If it is red straight away, then pH is likely really high, if it still starts yellowish/orange and then turns red, the initial reading counts.

You can make a 50:50 dilution of your pool water sample with distilled water (not tap water) and use that to test pH. Because pool water is buffered (it has a sufficiently high TA) and distilled water is unbuffered, the pH of the water sample stays more or less unchanged by this, but the FC gets halved and doesn't interfere with the pH test anymore.
My FC generally runs between 15 and 20.

Not sure where I'd get distilled water. I assume a pharmacy should have it, no?
 

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proavia

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Feb 6, 2015
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Plain old distilled water - no Smart Water or similar. Pretty much any grocery store should have it. It's usually in a gallon jug.
Lots of uses.... use in a humidifier, use in a steam iron, use to top up your car battery, etc. - in addition to the use mentioned above.
 
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JoyfulNoise

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May 23, 2015
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Two thoughts -

Please post a full set of test results for your pool water. Talking about specific chemical levels in isolation does no good.

Myths about pH/Heaters/Etc

There is no such thing as a "bullseye pH" or "optimal pH" or any such thing as it relates to specific equipment in general or heaters in particular. Your heater is much more likely to not work because of a system issue (not enough gas pressure, bad sensor reading, improper flow, etc, etc) than a chemistry issue. People think that because there is science surrounding corrosion in one part of life, eg, road salt corrodes my chrome bumper OR calcium scales out inside my SWG, etc, etc, that it necessarily applies exactly to all other aspect of life. Simply untrue. Corrosion or scaling inside of a heater are very specific phenomena that have their limits and conditions when those types of processes apply. Just saying "my pH may be high or out of range" is not specific enough to be able to know what impact that would have on a heater or if there would be any impact at all. This is why a FULL SET of test results is important.

The two primary chemical processes that could potentially kill a heater's copper heat exchanger are scaling of calcium carbonate because the CSI of the water is too positive OR etching (dissolution) of the copper surface due to very low pH. If you post test results, then it can easily be determined if scaling is possible. Note that I said "possible" ... while saturation indices tell us what is possible they do NOT predict what will happen exactly. As for copper being etched or removed, that is almost totally impossible at normal pool pH ranges (7.0-8.2). Both bare copper metal and it's various oxides (passivation layers) are stable in that pH range. Only exposure to very acidic water (pH < 6.8) for long periods of time would degrade the copper metal surface. This is typically the case when people throw trichlor pucks in their skimmer - trichlor is very acidic and when the pump isn't running, the water in skimmer becomes very corrosive and acidic and then, when the pump turns on, a slug of low pH water hits the heater and does damage. This is one very good reason why chemicals should never be dumped into the skimmer.
 

summertimesadness

Well-known member
Aug 23, 2022
73
New Jersey
Pool Size
30000
Surface
Vinyl
Two thoughts -

Please post a full set of test results for your pool water. Talking about specific chemical levels in isolation does no good.

Myths about pH/Heaters/Etc

There is no such thing as a "bullseye pH" or "optimal pH" or any such thing as it relates to specific equipment in general or heaters in particular. Your heater is much more likely to not work because of a system issue (not enough gas pressure, bad sensor reading, improper flow, etc, etc) than a chemistry issue. People think that because there is science surrounding corrosion in one part of life, eg, road salt corrodes my chrome bumper OR calcium scales out inside my SWG, etc, etc, that it necessarily applies exactly to all other aspect of life. Simply untrue. Corrosion or scaling inside of a heater are very specific phenomena that have their limits and conditions when those types of processes apply. Just saying "my pH may be high or out of range" is not specific enough to be able to know what impact that would have on a heater or if there would be any impact at all. This is why a FULL SET of test results is important.

The two primary chemical processes that could potentially kill a heater's copper heat exchanger are scaling of calcium carbonate because the CSI of the water is too positive OR etching (dissolution) of the copper surface due to very low pH. If you post test results, then it can easily be determined if scaling is possible. Note that I said "possible" ... while saturation indices tell us what is possible they do NOT predict what will happen exactly. As for copper being etched or removed, that is almost totally impossible at normal pool pH ranges (7.0-8.2). Both bare copper metal and it's various oxides (passivation layers) are stable in that pH range. Only exposure to very acidic water (pH < 6.8) for long periods of time would degrade the copper metal surface. This is typically the case when people throw trichlor pucks in their skimmer - trichlor is very acidic and when the pump isn't running, the water in skimmer becomes very corrosive and acidic and then, when the pump turns on, a slug of low pH water hits the heater and does damage. This is one very good reason why chemicals should never be dumped into the skimmer.
I did a full test awhile ago.


I've been just monitoring the FC for the past few weeks before closing. But I remembered the water heater issue that was brought up by the pool inspector by a warning.. and knowing my FC level is above 10ppm.. figured I'd ask about the PH.
 
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mgtfp

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Odd Q, are there differences between different types of distilled water?

Such as smart water. They list themselves as distilled but add electrolytes for flavor. Would that mess up any tests?

No water that is sold for drinking.

What you need for this purpose is sold in the household or cleaning products aisle.
 

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