Formula for bringing salinity down from 1.025 to 1.009

[cthetoy]

My refractometer is calibrated at 1.025 using the Pinpoint solution however I suspect I have a slope miscalibration meaning its accurate at 1.025 but measuring salinity at a lower level its not accurate.

So does mixing 1L of salt water with salinity of 1.025 with 1L of RO/DI water will bring the salinity to 1.0125 or rounding to 1.126? If not how many liter of RO/DI water do I need to mix 1L of 1.025 salt water to 1.008 for hyposalinity treatment

[disc1]

Put your measurements into ppt and you can use C1V1 = C2V2.

Basically it works like this. The concentration of a solution times the volume tells you how many molecules of salt are there. It may be in funky units (once we worked this out using dixie cups full of salt and homer buckets full of water for the units) but it still works.

Since you don't add any salt, only more water, that product should remain the same. The only thing that changed is concentration and volume.

So take 1L at 35ppt and we want to bring it down to say 25ppt.

(35 ppt * 1L) = (25 ppt * x) we don't know what the new volume will be. Let's calculate.

35 * 1 / 25 = 1.4 So the new volume would be 1.4L. So we would need 400mL to get 1L from 35 to 25.

Substitute in the numbers you need and you should get there.