pH Measurement - Hanna vs Apex

[BiggestE22]

Oxygen has nothing to do with pH

Yes correct. It’s CO2 that does.

 

[BiggestE22]

I've been using the Hanna pH Checker (HI780) for a few months now and i've always had really good pH readings (8.1 - 8.5).

I recently installed an Apex and am getting pH of 7.6 - 7.8 - I thought the pH probe was off and calibrated it numerous times and still seeing the same readings. Which reading should i trust? I'm beginning to feel the Apex readings are right. I do not dose kalkwasser or have a co2 scrubber.

No kalk or scrubber and not connecting the skimmer intake to an outdoor source will likely cause a sub 7.9 PH

 

[Malcontent]

CO2 and O2 annihilate each other like matter and anti-matter.

 

[ProxyAquarist]

SlugSnorter, Hllb, ... et al have given great advice that follows the rule, "When in doubt verify."

As others noted for this, all the parameters must be equal. So same temp., same air pressure, samples taken from the same location, ... etc. Ideally I'd "bench test" both the Apex and Hannah test kits with one calibration solution. In this case, I'd keep the Apex probe in a KCL storage solution between tests and use DI/RO water to clean the probe or Hannah cuvette between tests. I'd also repeat the test for each a number of times to get a good ample size (5 times?).

So what if the two tests do not match? This is common in science. The bottom line is "Are both consistent?" If the data for both are consistent and parallel each other, I'd continue with both. As aquarists, we watch for changes. Avoid being a slave to numbers. Someone said, "Nothing good happens fast in reefing." Give yourself time to think it out. Asking the experts here was a great start.

Trust your judgement. Watch your tank inhabitants. If they look content, hold off. I use the same maxim used in medicine, "Do no harm."

Yours in reefing and tackling the unexplained,
Jim

 

[piranhaman00]

Ok take it literal then....

Decrease in Co2 or increase in O2.

Higher O2 concentration or the decrease of Co2 will cause PH to rise.



Sorry if I wasn't being technical enough for you.

It’s ok, I know you’ll do better next time!

 

[AJsReef]

I purchased a HI780 as an attempt to validate my Apex occasionally. Even with multiple different reagents sent from Hana the tester could never accurately test values above 8.1 pH. I trust a calibrated pH probe over the handheld any day.

 

[Mindblock769]

I went ahead and purchased a pH hand held meter from amazon. It's probably not the most accurate meter out there, but after calibration it matches the Apex within .1 - So after all these months of using the Hanna meter, i believe it has been wrong. I trust the Apex probe now.

 

[plankton]

So trying to maintain ph range so bought Hanna tester just to see what the values would be versus my calibrated ph probes (7 and 10 stds)

I calibrated the pH probes twice with 7/10 standards after allowing them to get to tank temperature.

How accurate is the Hanna meter? Instructions mention accuracy +/- 0.2 pH.

There is no calibration procedure in the documentation. Numbers are way off …

Meter	75gallon	25 gallon
Hanna	8.4	8.6
pH probes	7.89	8.17

 

[elcapitan1993]

Are you using c02 media with your skimmer? I noticed that the Hanna ph checker gives skewed results if your using that stuff, once I took it off my tank about a week later my probe was closely matching the Hanna checker

 

[plankton]

Are you using c02 media with your skimmer? I noticed that the Hanna ph checker gives skewed results if your using that stuff, once I took it off my tank about a week later my probe was closely matching the Hanna checker

Yeah I’m using soda lime with skimmer

 

[elcapitan1993]

Yeah I’m using soda lime with skimmer

Yeah then that would be why, I bet you if you take that off for about a week the Hanna ph checker will read closely with the ph probe, and if you don’t want to take that off then trust the ph probe, it doesn’t get affected by the soda lime

 

[TheHunterYall]

For fun I just did the salifert test on ph cal solution, lol. 3ml 7 and 2ml 10. Theroically it is 8.2 and it looks like the salifert 8.3 color before and after. Maybe it got a tad darker after.

 

[TheHunterYall]

For fun I just did the salifert test on ph cal solution, lol. 3ml 7 and 2ml 10. Theroically it is 8.2 and it looks like the salifert 8.3 color before and after. Maybe it got a tad darker after.

And my probes read 7.9 to 8.0 and salifert interpretation is 8.0 to 8.15 so I tend to trust probe but hopeful it’s a tad higher. Also after thinking about this often and calibrating.

 

[ScubaScott]

I've been using the Hanna pH Checker (HI780) for a few months now and i've always had really good pH readings (8.1 - 8.5).

I recently installed an Apex and am getting pH of 7.6 - 7.8 - I thought the pH probe was off and calibrated it numerous times and still seeing the same readings. Which reading should i trust? I'm beginning to feel the Apex readings are right. I do not dose kalkwasser or have a co2 scrubber.

Did you have the Apex temperature sensor as well? If so, I recommend going into the Advanced tab for the pH sensor settings and checking the box to turn on temperature compensation. You will have click the button to send the new setting to the Apex, and then you will have to redo the calibration. For calibrating, I bought a kit with bottles of 4, 7, and 10 ph reference solutions. I calibrate with the 7 and 10 and check the probe against them after calibrating. The probe reads spot on with the reference solutions after cal and agrees very closely with a Red Sea chemical pH test kit that I have. FYI, I also have a Hanna H1780. It is junk. I have had two and both give consistently nonsense high values while the Apex and Red Sea kit (two completely different measurement methods) agree with each other and give sensible values. The Hanna kit will give a flashing 8.6 (meaning pH to high for the instrument to measure) for fresh mixed RODI salt water.

 

[ProxyAquarist]

... For calibrating, I bought a kit with bottles of 4, 7, and 10 ph reference solutions. I calibrate with the 7 and 10 and check the probe against them after calibrating. The probe reads spot on with the reference solutions after cal ....

I agree with ScubaScott, I also have 4, 7, 10 standard solutions for calibrating my lab pH meters, and I follow a similar procedure. The pH probes are calibrated at least monthly and before important readings.

My son just got a Apex as a gift and the plan is to use the same technique for its setup. Thanks for the heads up on the advanced procedures and temperature correction.

Have a great 2022 !
Jim

 

[Mindblock769]

Thanks for the tips guys. I will try calibration with 3 solutions rather than two.