Test Kits

msujohn

New member
I am using the red sea kits for Alk,Cal, and Mag. I seem to have a little trouble determining when the color really changes. For instance with Alk - I tested several times and get somewhere between 7.0 and 7.5. That range seems to be a little to great. I realize it is a little subjective based on when the color actually changes.

I'm using the Sailfert Phosphate test, which is just about useless to me.

So my question is should I get a Hanna checker (for Alk and Phospate)? Are they really that much easier to use and more reliable. Is there any subjectivity to this test as well?
 

bertoni

Premium Member
The Checkers are easy to read and require no subject color assessment, but not necessarily more accurate or reliable. Is the alkalinity kit set up so that one drop is 0.5 dKH?
 

msujohn

New member
The Checkers are easy to read and require no subject color assessment, but not necessarily more accurate or reliable. Is the alkalinity kit set up so that one drop is 0.5 dKH?

It's based on the amount of ml tritant used. So 0.5 ml used equates to a 7.0 alk an 0.54 used is 7.6. To me it's very subjective. Maybe I'm not use to the test yet (i've only used it 7 to 10 times).
 

bertoni

Premium Member
Well, I suspect that with some practice, you might close down the range a bit, but not all that much. That range should be okay in practice, though.
 

Scorpius

Stick Head
I find my hanna checker for alkalinity unreliable. Even when I do everything the same I will get two different results each time. I use Red Sea for Alkalinity, Hanna Checker for Calcium, and Salifert for Magnesium.
 

Scorpius

Stick Head
How far apart are the results?

It's weird because at times they are only .1 off of each other with the Red Sea usually reading .1 higher than the Hanna Checker. Yesterday I had a 9.2 with my Red Sea alkalinity test and an 8.7 on the Hanna Checker. I hate having to test again on the Hanna Checker because you don't have that many tests in a bottle.

With the Hanna Checker I always wipe the vial off to make sure there are no smudges or fingerprints. I always make sure to face the 10ml mark the same way in the checker also.
 

bertoni

Premium Member
9.2 and 8.7 are close enough for our purposes, although it'd be nice to have a bit more accuracy.
 

msujohn

New member
9.2 and 8.7 are close enough for our purposes, although it'd be nice to have a bit more accuracy.

Is this really close enough? I was worried when I do the tests with my Red Sea kit and get differences of 0.5 that it was a big issue.
 

toothybugs

New member
You can always do testing in triplicate to verify results, I find I like to do that if something seems off. Funny how many times you get a different result, but after a while (and getting an eye for color shifts) it's nice to get results that look like "1320 - 1360 - 1340" or something similar. It's relatively spendy to test that much but you will definitely feel better about your results. Also, if your values end up all over the place, it shows you where some error may be coming in.

I have the same kits and small drops and long dispersion/ shake times will help out your consistency quite a bit, particularly as you approach the end of the titration. I also overshoot what I think is the end of the titration to ensure color flip. You get an eye for what is "mostly blue" and "truly blue" pretty quick that way.
 

bertoni

Premium Member
I don't think tanks are likely to perform very differently whether the alkalinity is 9.2 or 8.7. "Close enough" is a bit subjective, though.
 

swk

New member
I find the salifert alk kit has a more obvious end point than the Red Sea. I use Red Sea for ca and mag, but switched to salifert for alk. Much easier IME
 

tmz

ReefKeeping Mag staff
Premium Member
I use a hanah 713 colrimeter for PO4 ; it is very consitent . I also use the alk checker with consistent results. The digital readouts are easier on my eyes than interpreting c tints of color.
 

erndog1001

Premium Member
Has anybody used Salifert and Red Sea Alk tests side by side? I've been using Salifert for a while and decided to give Red Sea a try based on a conversation I had.
The results are WAY apart. I.e. Say I get a reading of 6.5 dKH with Red Sea. Salifert will say 8.5 dKH or even higher!! And I've tested side by side enough to eliminate human error. Also I agree that Red Sea's color change is quite vague and subject to interpretation.
 

bertoni

Premium Member
I think the Salifert kits come with a reference solution? You might try testing that. Also, kits often will tend to read lower over time as water evaporates from the solutions.
 

erndog1001

Premium Member
I think the Salifert kits come with a reference solution? You might try testing that. Also, kits often will tend to read lower over time as water evaporates from the solutions.

TY But Im using Fusion Not the chart and Im told its already adjusted. And how can water evaporate from a closed bottle?
 

bertoni

Premium Member
When you open the bottle to remove the titrant, some air gets exchanged with the bottle, so the reagents lose some water.
 
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