Salifert Potassium test

[Koty]

Is it known why this test kit gives underestimated values when it’s reagents are almost emptied?
I got a reading of 310 ppm that turned out to be much higher using the Tropic Marin K test (n=3).

 

[Randy Holmes-Farley Verified Community Expert]

I’m not aware of such knowledge.

 

[spsick]

It’s a tricky test as is, but if it’s old enough to be used almost up I’d wager it’s expired?

 

[Miami Reef]

I think @Reefer Matt had a similar experience?

 

[bubbgee]

Is it known why this test kit gives underestimated values when it’s reagents are almost emptied?
I got a reading of 310 ppm that turned out to be much higher using the Tropic Marin K test (n=3).

What's your confidence in the salifert test? I was thinking of getting that.

 

[Reefer Matt]

I think @Reefer Matt had a similar experience?

For me, the color change was too subtle, and it was a new test kit. I ended up overdosing the tank because I thought it was low. The reason I tested was when I changed salt and my tank nearly crashed, I thought low potassium may be the problem. Then adding too much of it didn’t help. I ended up switching back to RC with large wc’s and the tank recovered.

 

[Koty]

I added the missing potassium according to the test without making any calculation mistakes but afterwards The TM kit I decided to start using gave me a 550ppm reading. As I do not do WC my tank consumes potassium. The salifert test is rather simple and usually seem consistent IME. No apparent negative effect… yet. Hope tank will consume K back to normal values.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, I never dosed any and iCP showed potassium was spot on.

 

[Koty]

These are two K tests periods. The 1st shows the ppm values on the left and the 2nd shows the recent measurements. All measurements done before supplementing K.

 

[FishLvR]

I personally have a much easier time with Nyos's potassium test kit. It's the only kit of theirs I buy because I can see the color change. I use Salifert for everything else.

 

[FishLvR]

Wait, potassium....I mean phosphate, just ignore the hell out of me.