Are test kits giving you trouble?

[matt-davis sq.]

Are you tired of getting results that vary from one day to the next?

Is the color indicator difficult to observe?

Do you require the optimal lighting just to observe the color indicator?

Are you mildly color blind, like myself, and physically unable to observe the subtle color changes most test kits use?

Are you dissatisfied with the lack of precision?

...well then, take matters into your own hands!

Do your own test! The following are the results from a titration to determine alkalinity:

Starting the titration:
http://www1.coe.neu.edu/~mlitman/start.jpg

At the end of the titration:
http://www1.coe.neu.edu/~mlitman/finish.jpg

The titration curve:
http://www1.coe.neu.edu/~mlitman/curve.jpg

The indicator used was methyl orange. Unlike for home test kits, which rely on a color change to observe the end point, the indicator used here is completely unnecessary. The end point (pH 4.3) is determined from the titration curve.

The volume of 0.02N H2SO4 required to bring a 50mL sample of tank water to a pH of 4.3 was 8.40mL, which corresponds to a bicarbonate concentration of 3.36 x 10^-3 mol/L = 3.36 x 10^-3 eq/L = 3.36 meq/L.

In other words, the calcium reactor is working!

Matt:cool:

P.S.: I do not want this post, which is partially in jest, to be taken as a blanket criticism against test kits. Test kits are very helpful to all of us, for ordinary people do not have access to such laboratory equipment. As you notice, I do not mention which test kits I was using, as I do not want this e-mail to be taken as a criticism towards any one manufacturer. Overall, I have seriously been very pleased with over the counter test kits with the exception of finding some of the color changes hard to detect.

[R Baxley]

LOL.

I used to be annoyed that my salifert alk test had 2 dif components!

[Groove]

Originally posted by matt-davis sq.
Are you tired of getting results that vary from one day to the next?

...with the exception of finding some of the color changes hard to detect.

I hear that!

I bought a pH meter because of this. I wish I could find an easy way to check calcium. As of right now the only tests I trust are pH through a meter and Greg Hiller's Alk test. Any tips Matt???

[masterswimmer]

Originally posted by matt-davis sq.

The volume of 0.02N H2SO4 required to bring a 50mL sample of tank water to a pH of 4.3 was 8.40mL, which corresponds to a bicarbonate concentration of 3.36 x 10^-3 mol/L = 3.36 x 10^-3 eq/L = 3.36 meq/L.



You've got to be kidding me!!!

[Pyrojon]

YES, He Is

[matt-davis sq.]

You've got to be kidding me!!!I'm not sure what you mean... I double checked the math...

Matt:cool:

[matt-davis sq.]

I bought a pH meter because of this. I wish I could find an easy way to check calcium. As of right now the only tests I trust are pH through a meter and Greg Hiller's Alk test. Any tips Matt???What is Greg Hiller's Alkalinity test?

To answer your question, I had been thinking about putting together a thread for people who want a serious and accurate assessment of their tank parameters and are willing to invest in some basic scientifice equipment. After all, why invest so much money in a system that cannot be monitored precisely?

Just as a pH test kit is no substitute for a pH meter, on the same scale, the alkalinity test kits are ni substitute for the titration I performed. Coincidentally, the alkalinity titration I performed is simply a larger scale analog to the test kit titration. However, unlike the alkalinity test kit, my method uses a pH meter to observe the equilibrium point rather than a color indicator.

Fortunately, the test kits available are all scaled down versions of standard laboratory experiments. Calcium can easily be determined through a titration as well, using EDTA to bump HNB off of a calcium-HNB complex in solution, after raising the pH to precipitate magnesium.

I would be more than willing to post about what equipment is required to perform these experiments for calcium and alkalinity.

Matt:cool:

[Greg Hiller]

Matt,

I make a alkalinity kit from bromophenol blue and HCl. Works great. VERY accurate. No pH probe required. Accuracy increases with sample size, though for what we are doing you don't need incredible accuracy, you just need to know its above 2.5 and below 3.5 meq/l (IMHO). Great for testing if your calcium reactor is working also, by directly testing the effluent. We have given the reagent out at our meetings before (you must have missed the boat!).

I also found out how to make the reagent for the HACH calcium test kit. The only thing I have to purchase for that kit now is the reagent packet. I think it costs about 10-20 cents per test for me now. I also dilute my water samples before I perform this test, saves on reagent, and the end point is easier to see.

The only other test I perform, and only occasionally (maybe once every two months) is the Mg kit from Salifert. I'm pretty happy with that kit although the reagents do age after about 2-3 years (get lower numbers than is accurate).

There are NO hobbiest kits available that accuratly measure Sr. Too bad, because I think it'd be interesting to do some experiments with Sr. Randy H-F uses ICP analysis, but it's going to take me a long time to save my dimes to purchase my own ICP!!!

[Groove]

Does that mean you might offer calcium test kits soon???

I hope so. My Red Sea test kit is useless.

[Keith Sheridan]

My name is Keith Sheridan, and I am a color blind reefer.

[Groove]

LOL Keith

[matt-davis sq.]

My name is Keith Sheridan, and I am a color blind reefer.I'm laughing too, but imagine my anger when I pay $20 for a test kit, only to have the color indicator work by changing from a pale pink to a pale grey. I was like: ***!

Matt:cool:

[ME2003]

To answer your question, I had been thinking about putting together a thread for people who want a serious and accurate assessment of their tank parameters and are willing to invest in some basic scientifice equipment.

I would be interested. I would also be interested in how
different test kits work. This add chemical A to chemical B
does not give a lot of confidence as to what is being
measured. I have seen test systems before that use
spectrophotometers. Any information on these.

[Keith Sheridan]

Matt, I am not joking I am color blind.

Man, pink to grey, you would think that would be easy right, but they look the same to me.

[nickoz]

yeah I know of a couple BRS members who are also color blind.. makes test kits difficult for sure.

-nick