Hanna vs salifert. Which do i trust

[James Mikell]

So my salifert alk says 8.9. Hanna says 8.6 which test do i trust. I get repeatable number using both tests as i follow the same procedures for each.

 

[jsker]

I like the Hanna

 

[cracker]

James , I have the same issue . Used to drive me nuts ! Which one was right ? I chose the Hanna & stopped worrying about it . Every different kit will give You a different result.
The Hanna is so much easier to use & I'd rather be low than too high .

 

[Larry L]

Those are basically the same, within the range of test kit error. Hanna says the accuracy of the HI-772 alk checker is ±0.3 dKH ±5% of reading, so if it reads 8.6 dKH, the actual value could be anywhere from 7.9 dKH to 9.3 dKH. No idea what the accuracy of the Salifert test is, but probably has a similar range of uncertainty.

I wrote a calculator that lets you enter your checker readings to see what range the actual value might fall into: http://larryl.emailplus.org/fish/test-kit-calculators.html

 

[ScottR]

James , I have the same issue . Used to drive me nuts ! Which one was right ? I chose the Hanna & stopped worrying about it . Every different kit will give You a different result.
The Hanna is so much easier to use & I'd rather be low than too high .

How I approach this is: stability. If you can keep your values around the same, there is no need to worry about your alk being too high or low (assuming the margin of error is within an acceptable number). Going crazy chasing parameters is what throws it out of sync.

 

[JimWelsh]

Use Salifert with this endpoint: Alkalinity titration endpoint pH & Salifert endpoint color

 

[James Mikell]

Use Salifert with this endpoint: Alkalinity titration endpoint pH & Salifert endpoint color

Wow that was an incredibly eye opening thread and i thank you for pointing me to it. Going by that color scale to determine alk i have absolutely been over titrating the salifert kit and it would likely fall closer in line with the 8.6 of the hanna kit. I will retest tonight to confirm this new finding. Again thank you for your help

 

[Dkeller_nc]

BTW - regardless of whether you're misinterpreting the Salifert end-point, Larry has this correct - there is no difference between 8.6 and 8.9 dKH readings on a hobbyist test kit. It is possible to determine the acid buffering capacity (not quite the same thing as carbonate concentration, but close) of a sample of seawater/tank water to a high degree of precision, but that requires a pH titration with a standardized HCl solution.

The bottom line, though, is that 2 decimal point high-precision alkalinity estimation with standardized acid titration is a very high degree of overkill for a reef aquarium. Only us chemistry geeks do it. ;)