Salifert KH test reading

[limis]

Hi,

I am bit confused how to read Salifert KH test.
Do I need to stop dosing second reagent when color starts changing to pinkish or I stop when reagent becomes of color solid pink ?

 

[RajM]

Usually it would change from blue to purplish and next drop would be pink, that’s where I usually stop unless it’s not pink enough. I always check it against a white background in proper light.

 

[FishLvR]

Salifert says, after I emailed them, the reading is when it turns solid pink.

 

[Randy Holmes-Farley Verified Community Expert]

Yes, solid.

 

[gsxrshane]

I struggled to read the correct “pink” color for a while so I just ended up getting the Hanna Will never go back

 

[Randy Holmes-Farley Verified Community Expert]

I struggled to read the correct “pink” color for a while so I just ended up getting the Hanna Will never go back

It’s even easier if you just use a pH meter and ignore the color. pH 4.2 is the endpoint and that is how I determine alk:
https://www.reefedition.com/a-diy-alkalinity-test-by-randy-holmes-farley/

 

[RobertK]

I remember way back in chemistry lab they taught us that for these types of reactions you should keep adding to the mixture until the color change is complete. I use that rule for the Salifert Ca, Alk and Mg tests and I think it helps me get consistent results. (And yes I know Randy and others advise against testing Mg, but I've never had a problem with it AFAIK using this method.)

 

[limis]

thanks for the replies

 

[MBruun]

When I double checked the KH values using other brands, Salifert matches NYOS, AF and Oceamo ICP - when the color start to change - and I get higher value if I make the reading with solid pink

 

[gbroadbridge]

Yes, solid.

My experience with the Salifert test is that if you titrate until the color change is complete, the result will be high by 0.3 to 0.6dKh compared to a manual acid/pH test.

I always stop at purple.

Of course, in practice, consistency is rather more important than the actual number.

 

[limis]

When I double checked the KH values using other brands, Salifert matches NYOS, AF and Oceamo ICP - when the color start to change - and I get higher value if I make the reading with solid pink

I don't like it since it contradicts to earlier posters and what Salifert support replied :)

 

[Randy Holmes-Farley Verified Community Expert]

Most people do not agonize or even care about a 0.3 dKH offset. I certainly don’t.

 

[FishLvR]

It’s even easier if you just use a pH meter and ignore the color. pH 4.2 is the endpoint and that is how I determine alk:
https://www.reefedition.com/a-diy-alkalinity-test-by-randy-holmes-farley/

Same. Edited to add wish I had read this before I decided to use this method. I should learn that most everything I want to try is on this website.