What ph number to believe

[Randy Holmes-Farley]

FWIW, I’m skeptical that any hobby equipment or tests that actually supply accuracy ranges (most don’t) have any data to validate that claim, and if they do, they certainly do not indicate what it even means (that is, what were the conditions of validation).

For a pH meter, does it include uncertainty in calibration (which itself is subject to pH measurement and pH buffer errors), does it include salinity effects? Temperature effects? User errors (not waiting long enough, waiting too long, too much stirring, too little stirring), electrical interferences, bacteria on probe, etc.

 

[gbroadbridge]

Wow, all this fuss over 0.2 pH uncertainty in a fish tank

 

[arking_mark]

Wow, all this fuss over 0.2 pH uncertainty in a fish tank

What's worthwhile is understanding the limitations of hobby grade test equipment.

 

[Lionfish hunter]

Wow, all this fuss over 0.2 pH uncertainty in a fish tank

To be fair, the difference between 8.1 and 8.3 is massive.

 

[Lionfish hunter]

FWIW, I’m skeptical that any hobby equipment or tests that actually supply accuracy ranges (most don’t) have any data to validate that claim, and if they do, they certainly do not indicate what it even means (that is, what were the conditions of validation).

For a pH meter, does it include uncertainty in calibration (which itself is subject to pH measurement and pH buffer errors), does it include salinity effects? Temperature effects? User errors (not waiting long enough, waiting too long, too much stirring, too little stirring), electrical interferences, bacteria on probe, etc.

Agree

 

[Lionfish hunter]

Did you try this? Did either probe get close?

My spare air pumps are supplying air to copepod and phyto cultures. I will try eventually.

 

[gbroadbridge]

To be fair, the difference between 8.1 and 8.3 is massive.

In a textbook, yes.

 

[BeanAnimal]

Curios as to what active automated mechanism will be used to precisely adjust the system pH as it fluctuates by the minute/hour throughout the day?

 

[mbmartin06]

Curios as to what active automated mechanism will be used to precisely adjust the system pH as it fluctuates by the minute/hour throughout the day?

I find telepathy and not checking works for me

 

[JimWelsh]

To be fair, the difference between 8.1 and 8.3 is massive.

Edited because I was wildly incorrect.

2nd edit to try to get it right: It depends upon how you define "massive". The difference is 2.93 * 10^-9, or 0.00000000293 moles per liter of protons, while water contains 55.5 moles per liter of water atoms. It really is a tiny change, in the context of how many water molecules there are.

 

[Lionfish hunter]

In a textbook, yes.

In coral growth too

 

[Lionfish hunter]

Edited because I was wildly incorrect.

2nd edit to try to get it right: It depends upon how you define "massive". The difference is 2.93 * 10^-9, or 0.00000000293 moles per liter of protons, while water contains 55.5 moles per liter of water atoms. It really is a tiny change, in the context of how many water molecules there are.

The comparison to the total amount of atoms in water is in no way a fair comparison. What is the percentage difference in hydrogen ions only from 8.1 to 8.3?

 

[JimWelsh]

The percentage difference of a 0.2 pH change is always 1-10^0.2 = 0.58, or 58%. That's true whether it's 8.1 to 8.3 or 0.1 to 0.3 or 13.1 to 13.3.

 

[Lionfish hunter]

The percentage difference of a 0.2 pH change is always 1-10^0.2 = 0.58, or 58%. That's true whether it's 8.1 to 8.3 or 0.1 to 0.3 or 13.1 to 13.3.

Yes a 58% difference is substantial.

8.1 to 8.3 looks like it is only a 2.5% difference if you didn’t know better.

 

[Lionfish hunter]

Curios as to what active automated mechanism will be used to precisely adjust the system pH as it fluctuates by the minute/hour throughout the day?

Why would you want to precisely adjust the system ph as it fluctuates? Are you concerned with ph stability to the point that you don’t want it to fluctuate? Because nobody on this thread has expressed concern with this but you have made multiple comments about it.

 

[BeanAnimal]

Why would you want to precisely adjust the system ph as it fluctuates? Are you concerned with ph stability to the point that you don’t want it to fluctuate? Because nobody on this thread has expressed concern with this but you have made multiple comments about it.

LoL - I don't want to control anything. I was asking you in the context that you must have precision pH readings.

WHY do you need them (1 tenth accurate readings +/- 0) if you don't have a means or plan to act upon them? This entire thread is a circular conversation based on your need to have precise pH measurements for $1200 an inch coral because that coral grows best at some xxxx perfect pH.


Sorry, but none of this makes sense and instead it goes back to chasing an unimportant level of precision with a non precision instrument. I think we are here because you assumed that one or more of these devices was more precise than it is, not because it matters, but because it bothers you.

Asking again, why do you need to READ pH to 1 tenth of a unit of precision???

 

[arking_mark]

LoL - I don't want to control anything. I was asking you in the context that you must have precision pH readings.

WHY do you need them (1 tenth accurate readings +/- 0) if you don't have a means or plan to act upon them? This entire thread is a circular conversation based on your need to have precise pH measurements for $1200 an inch coral because that coral grows best at some xxxx perfect pH.


Sorry, but none of this makes sense and instead it goes back to chasing an unimportant level of precision with a non precision instrument. I think we are here because you assumed that one or more of these devices was more precise than it is, not because it matters, but because it bothers you.

Asking again, why do you need to READ pH to 1 tenth of a unit of precision???

Don't be too quick with your assumptions...

Thread 'Lessons learned in trying to maintain pH stability' https://www.reef2reef.com/threads/lessons-learned-in-trying-to-maintain-ph-stability.871213/

 

[BeanAnimal]

We are still going in circles.

Don't be too quick with your assumptions...

Thread 'Lessons learned in trying to maintain pH stability' https://www.reef2reef.com/threads/lessons-learned-in-trying-to-maintain-ph-stability.871213/

I am not sure what I have assumed?

You can hold your pH to .05 measured with a probe (alone) that has an advertised accuracy (not mention of ADC/software or temp correction accuracy) of +/- .2

So .05 of what?

I think we are running in circles here.

 

[arking_mark]

We are still going in circles.


I am not sure what I have assumed?

You can hold your pH to .05 measured with a probe (alone) that has an advertised accuracy (not mention of ADC/software or temp correction accuracy) of +/- .2

So .05 of what?

I think we are running in circles here.

It's possible to maintain a stable tightly-controlled pH with the right techniques. The true pH number is not that important...

 

[Steve2020]

It's possible to maintain a stable tightly-controlled pH with the right techniques. The true pH number is not that important...

I agree it is very much possible. The technique I use keeps what I consider a pretty tight PH window at the level I desire.
The swing you see from 6PM to 8PM is from my return pump and skimmer being shut down when I dose phyto and Pohl's Coral Vitalizer.

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