PH exceeding 8

[xDom]

A lot of literature will say that pH should be kept at a certain range for bather comfort or for chlorine effectiveness.

TFP debunks the chlorine aspect of this through the FC/CYA ratio and I haven’t actually read it but I’m pretty sure the bather comfort side of this is not true as well.

So, what is the issue if pH exceeds 8? If I’ve got my levels set up that the pH ceiling is say, 8.1, is there a problem with letting it sit at this and not using MA at all?

Edit: making sure the LSI is in check

 

[JamesW]

In my opinion, a pH of up to 8.3 is fine as long as the CSI is not over about 0.1.

I don't recommend a pH over 7.9, but if you want to go over 7.9 you need to be really sure about what the actual pH is.

Once you go past 8.0, you probably need a good pH meter to get an accurate pH reading since the color scale is really not designed for that level.

 

[JamesW]

PH60 Premium Digital Pocket Waterproof pH Meter pH Pen Tester Kit with Replaceable Probe and Backlight-Apera Instruments

The Apera Instruments PH60 Premium Digital Pocket pH Meter / pH Pen Tester is ideal for all kinds of regular aqueous solution's testing, such as hydroponics, aquaculture, pools& spas, water treatment, cooling towers, etc. Can be replaced with ORP probe.

aperainst.com

60 Series Portable Premium Pocket pH/EC/Salinity/TDS/ORP Meters and Testers

Apera Instruments 60 series portable premium pocket pH/EC/Salinity/TDS/ORP Meters and Testers are designed for regular multi-parameter measurements in soil, hydroponics, brewing, water testing, food and dairy products, and pools and spas.

aperainst.com

PC60 Premium Multiparameter (pH/EC/TDS/Salinity/Temperature) Pocket Tester/Meter Kit-Apera Instruments

The Apera Instruments PC60 Multi-parameter Tester/Meter simply tests pH/EC/TDS/Salinity/Temperature for regular aqueous solutions such as hydroponics, aquaculture, pools& spas, tap/drinking water, water treatment, cooling towers, etc.

aperainst.com

 

[JamesW]

PoolMath

 

[xDom]

In my opinion, a pH of up to 8.3 is fine as long as the CSI is not over about 0.1.

I don't recommend a pH over 7.9, but if you want to go over 7.9 you need to be really sure about what the actual pH is.

Once you go past 8.0, you probably need a good pH meter to get an accurate pH reading since the color scale is really not designed for that level.

Out of curiosity, how much credibility does the pH ceiling concept have?
If you were to wait until the pH were to totally stabilise, knowing the other variables could you then calibrate a pH meter to the pH ceiling value?

 

[JamesW]

Out of curiosity, how much credibility does the pH ceiling concept have?

I'm not sure exactly what a pH ceiling is.

The pH determines the amount of carbon dioxide, which determines pH rise.

If the level of CO2 in the water is equal to the level in the air, then the gain and loss of CO2 will be equal and there will be no pH rise from CO2 offgassing.

At a pH of about 8.3, the CO2 levels typically are low enough that the pH rise should stop or be very close to stopping.

I don't recommend going over 7.9, but I also would not have any concerns about going higher as long as the person knew exactly how to manage it.

Commercial pools are required to keep the pH within a specific range, so that is mandated by law and the operators need to follow the laws.

 

[JamesW]

The first graph is the percentage of bicarbonate vs. carbonate based on the pH.

The second graph is the percentage carbon dioxide (Carbonic acid) vs. bicarbonate.

At a pH of 8.0, most is bicarbonate.

 

[xDom]

I'm not sure exactly what a pH ceiling is.

On my LSI app it displays a pH ceiling. I believe it’s the maximum pH level that can be reached. It’s determined by the TA and CYA.
So with a TA of 55 and a CYA of 65 it tells me the maximum pH is 7.92.

 

[xDom]

At a pH of about 8.3, the CO2 levels typically are low enough that the pH rise should stop or be very close to stopping.

So in this case what could be a consequence?
Is it damaging to equipment?

 

[JamesW]

Is it damaging to equipment?

As long as the CSI is 0.0 or lower, the equipment should be fine.

If you have a gas heater, then the temperature in the heat exchanger can be substantially higher and you need to take that into consideration.

Higher temperatures cause the CSI to increase and you can scale out a heater and the warranty can be voided by the manufacturer for scaling.

 

[duraleigh]

xDom.

I don't think it is good pool water management to keep pH above 7.9. If you are simply trying to "trick" the parameters, them you can likely get away with it but the TFP guidelines are there because they work.......in virtually every circumstance.

Our parameters are "safe" and, particularly if your pool is fairly new to you, they have comfortable margins as you are learning.

 

[xDom]

As long as the CSI is 0.0 or lower, the equipment should be fine.

If you have a gas heater, then the temperature in the heat exchanger can be substantially higher and you need to take that into consideration.

Higher temperatures cause the CSI to increase and you can scale out a heater and the warranty can be voided by the manufacturer for scaling.

Reading your other posts you seem to be very strong in chemistry.
Could you let me know if you agree with that pH ceiling concept I mentioned? Could you see this as being scientifically accurate?

It actually comes from the Orenda site and I know there’s some negativity towards that here on this site. It doesn’t mean that everything they say is false though.

 

[JamesW]

Could you let me know if you agree with that pH ceiling concept I mentioned?

Basically, yes, it is a valid concept.

If the level of CO₂ gets low enough, the pH will not rise due to carbon dioxide offgassing.

The pH can still rise from other causes like the addition of any sort of base, but not from carbon dioxide offgassing.

 

[proavia]

It really doesn't matter if that pH ceiling concept is accurate or not within the context of the TFP website.
If you want to discuss it further maybe start a new thread, specific to that concept, in "The Deep End ..." forum.

As Dave (@duraleigh) mentioned, the TFP guidelines are there because they work.

If you are going to check the pool water chemistry all year, follow the guidelines.
If you are going to winterize your pool for the winter, don't test the pool water.

If you have a heater, it should be fully winterized to protect the heat exchanger and pipes from freezing and possibly cracking during freezing weather.

 

[JamesW]

The solubility of carbon dioxide in an uncovered swimming pool is determined by the Henry's Law Constant for CO2 at the pool water temperature, and by the partial pressure of carbon dioxide in the atmosphere.

The solubility is in the 0.53 to 0.57 ppm range.

In pool water the concentration of CO2 will usually be in the 1 to 10 ppm range depending on the TA, pH etc. because it is in equilibrium with bicarbonate and carbonate.

Because it is above its inherent solubility, it constantly off gasses, which causes pH rise.

The off-gassing is typically fairly slow as long as the concentration of CO2 does not get too high.

The concentration of CO2 increases as the pH is lowered and/or the carbonate alkalinity is increased. In areas of lower pH, the CO2 levels will increase and off-gas faster.

CO2 and pH: Understanding Henry's Law

The pH of a swimming pool is determined by how much CO2 is in solution. Henry's Law explains why CO2 leaves the water, and when it does, pH rises naturally

blog.orendatech.com

PH TA Relationship - Further Reading

www.troublefreepool.com