High alkalinity on fresh salt water mix

[tezaman]

Hi all, I need help

I am trying to make a decent fresh water mix with alkalinity 8-10 , the salts that I am using was various .
Today I tried Red sea Blue bucket which is specifically low alk.
After the salt completely dissolved I measured alk and is 13kh !

I measured my RO and is 7 .

 

[Reef.]

Your salinity is most likely off, or your testing is not correct, as Red Sea blue is around 8.5, no way will it be as high as 13.

 

[tezaman]

Your salinity is most likely off, or your testing is not correct, as Red Sea blue is around 8.5, no way will it be as high as 13.

No this is not the case my salinity is 35 ppt spot on
I calibrated the refractometer with salifert calibration liquid

 

[tezaman]

On the exit of my RO I measured KH at 7 thought , is this the case ?

 

[tezaman]

My testing is a brand new salifert kh with 2025 exp date.
I will get a Hanna later .

 

[Garf]

On the exit of my RO I measured KH at 7 thought , is this the case ?

RODI has a zero Dkh value if it’s working properly. Is yours just RO? Have you measured the tds of it?

 

[Reef.]

My testing is a brand new salifert kh with 2025 exp date.
I will get a Hanna later .

Salifert is as good as Hanna for kh, could be your testing incorrectly.