hanna alk checker post your results

[Art2249]

Alk and calcium levels are not affected by ambient CO2 levels. pH is. Your anecdotal observation implies that perhaps the Hanna alk checker is sensitive to pH changes. I own a Hanna checker, but rarely use it. I wonder if others have reported a similar pH-sensitivity?

I agree that alk and calcium are not affected by ambient co2. However alk and calcium USAGE are effected by ambient co2. In other words, your tank will use these elements faster when you open the windows.

 

[2una]

Cool! I would like to add one point that makes this topic so difficult. My alk levels are consistent so long as my house is closed. once i open my windows and doors i find that i need to add alk and calcium accordingly. usually that amounts to .1 alk and the corresponding amount of calcium. Which in my tank is 11 ml each.

Try looking at your pH with house closed up vrs open & maybe you might become a follower in the belief that higher pH drives more growth & thats why your Alk/Ca declines

 

[Art2249]

Ok guys Ill be using a spreadsheet like this. Just did the test. Got a discrepancy of 0.6 dKH.

Try doing the hanna test without the syringe extension!

 

[Art2249]

Try looking at your pH with house closed up vrs open & maybe you might become a follower in the belief that higher pH drives more growth & thats why your Alk/Ca declines

This is why I need to add additional alk and calcium when i open the windows. But I wish to go back to my original point. The hanna checker works better without the syringe extension.. try it and post your data!

 

[JimWelsh]

In other words, in a reef tank, a pH change is almost certainly going to correspond to an alkalinity change, and vice versa.

A pH change is almost certainly going to correspond to an alkalinity change, or a dissolved CO2 change, or a combination of the two.

However alk and calcium USAGE are effected by ambient co2. In other words, your tank will use these elements faster when you open the windows.

Good point!

 

[Art2249]

True and not true. The thing to remember is the pH and alkalinity are intimately connected. In other words, in a reef tank, a pH change is almost certainly going to correspond to an alkalinity change, and vice versa, even if we are not detecting this due to limitations on testing or the kinetics with which this is happening. pH levels are affected by ambient CO2 levels, via conversion to carbonic acid. This species is a key player in the Carbonate <-> bicarbonate <-> carbonic acid equilibrium in the tank. A Basic chemical principle is that in a state of multiple equilibria, all must be satisfied. In other words, if the ambient CO2 level rises, then the pH drops, and the equilibrium concentrations of one or more of the above must change to compensate.

Alk and calcium levels are not affected by ambient CO2 levels. pH is. Your anecdotal observation implies that perhaps the Hanna alk checker is sensitive to pH changes. I own a Hanna checker, but rarely use it. I wonder if others have reported a similar pH-sensitivity?

Please remember that I am talking about levels that vary based on if my house is opened up or shut off. i have found that my tank uses about 10 to 20 ml more alk and calcium when the windows are open. Lets go back to the basic question here. Use the hanna checker with the syringe extension and without. post your results.

 

[CMO]

What is the hypothesis as to why the extension would impact results?

And also, If we're trying to test the impact of the extension, why wouldn't you test the results using the same Hannah checker with and without the extension? How does comparing against Salifert help isolate this variable? It just brings another one in from what I can tell?

 

[dferran1]

good discussion guys.

Im going to do some more thinking about why opening the windows (decreasing the ambient Co2) might somehow increase calcium and alkalinity consumption.

 

[JimWelsh]

Ok guys Ill be using a spreadsheet like this. Just did the test. Got a discrepancy of 0.6 dKH.

How are you determining the Salifert endpoint? In other words, please describe the color you are using to identify the endpoint.

 

[Art2249]

What is the hypothesis as to why the extension would impact results?

i dont know what hypothesis means because i am not a scientist. But i did stay at a holiday inn express last night. Plus I graduated from Naval Nuclear Power School. So i guess that the hypothesis is whether the test works better one way or another!

 

[dferran1]

Jim,

I am following the instructions given by salifert. I continue to add the KH titrant until the color changes completely to pink. Usually a single drop accomplishes this transition from blue- green to pink. I am aware that there will be some titration error present in my results , and that my actual alkalinity in reality will be slightly lower than that measured by the Salifert kit. I am okay with this. I am willing to accept an error of what is likely to be a few tenths of a dKH unit for hobby purposes. Moreover, I am content just knowing that my alkalinity is stable in a certain acceptable range.

To speak to Arts comment above, it is important to remember we are all hobbyists, and indeed not everyone needs a rigorous scientific background to keep a successful reef tank.

Edit: the procedure I used for the hanna is as follows.
- I wore nitrile gloves from the dollar store while using the cuvette.
- I triple rinsed the cuvette with first ro/ di and then tank water, before adding tank water to the volumetric line on the cuvette (bottom of the meniscus)
- I wiped the cuvette with my refractometer cloth before zeroing the colorimeter, and then again before loading the sample containing the reagent.
- I used the syringe tip extension. I brought the line on the bottom of the piston to the zero mark at the top of the 1 mL syringe.

 

[Art2249]

How are you determining the Salifert endpoint? In other words, please describe the color you are using to identify the endpoint.

The color I am observing is the CHANGE. In other words as soon as the change in color starts I mark the results. Please correct me if I am doing the test wrong.

 

[CMO]

i dont know what hypothesis means because i am not a scientist. But i did stay at a holiday inn express last night. Plus I graduated from Naval Nuclear Power School. So i guess that the hypothesis is whether the test works better one way or another!

Well, you should probably do a bit of research then before you setup a flawed experiment like this. Look up Spurious Correlation which is what you are going to find with what you have going here.

 

[dferran1]

Art, I wouldn't say you are doing the test wrong per say. I just argue that following the instructions and going to the endpoint (full color change) will make things more reproducible. If you stop early, you are likely to have error as well, because you will not have hit the equivalence point. Waiting for the full color change, I am aware I have surpassed the equivalence point ever so slightly, and will have that error in my test results.

I guess the moral of the story is that we are all forced to accept some degree of error while using a hobbyist grade test kit. We should just try to keep this in the back of our minds, and in my opinion, aim for stability rather than chasing a certain particular number for a parameter, the actual value of which we never will really know. Even the triton ICP-OES testing will be accompanied by some degree of error, however small

 

[Art2249]

Try looking at your pH with house closed up vrs open & maybe you might become a follower in the belief that higher pH drives more growth & thats why your Alk/Ca declines

Here is a small example of that ph swing betwen windows open and shut

 

[Art2249]

I just started using dosing pumps. Before I was dosing by hand. The ph swings are smaller now.

 

[dferran1]

Art,
ever consider using Kalkwasser to help raise and stabilize the pH. This has worked for me. I am using it in addition to 2- part calcium and alkalinity supplementation. ( ESV Bionic)

 

[Art2249]

Well, you should probably do a bit of research then before you setup a flawed experiment like this. Look up Spurious Correlation which is what you are going to find with what you have going here.

You are correct! This is why i am not a scientist. Because i have never been to college!. However, that does not preclude me from collecting an analyzing data. And it also doesn't preclude me from running a vary nice reef tank. With very stable parameters. So I guess this is my attempt at doing "a bit of research" !!! Oh Galileo!

 

[JimWelsh]

The color I am observing is the CHANGE. In other words as soon as the change in color starts I mark the results. Please correct me if I am doing the test wrong.

FWIW I'm of the opinion that the correct endpoint color for the Salifert alk test is better described as a "lavender" color. Going all they way to pink is overshooting the true endpoint. For an example of the color I'm trying to describe, please see here: Salifert Test Kit and Hanna Checker Results for Alkalinity

For a more detailed explanation of why I think this is so, please read through the following thread starting here: Salifert KH/Alk testing help

 

[CMO]

You are correct! This is why i am not a scientist. Because i have never been to college!. However, that does not preclude me from collecting an analyzing data. And it also doesn't preclude me from running a vary nice reef tank. With very stable parameters. So I guess this is my attempt at doing "a bit of research" !!! Oh Galileo!

My full original post was simply trying to help improve your study. By testing the Hannah checker with water of a known dkh, against itself with and without the extension, vs. against Salifert will help you isolate (but not completely) what I believe you are trying to prove - that the Hannah checker is more accurate without the extension. Bringing in Salifert to prove this just adds another variable. How do you know the variation you are seeing isn't from the salifert test?