IO calc level low or refractometer off?

Thumbster · Jun 20, 2023

Well I got my scale today and it seems to be surprisingly accurate. I checked it several times with different weights and combined weights and it was dead on to the hundredth.

I also discovered my refractometer was only 1 ppt off. I mixed the solution to 35ppt and it was reading 34. That explains a small part of my low Ca but not the majority of it.

I did mix another couple gallons using the old salt and the Ca tested 360ppm. I’m going to mix a couple gallons from the new bucket tomorrow and measure it.

I’m also wondering if some of the calcium is precipitating out when I mix it. I usually mix about 4 gallons at a time using a bucket and a powerhead.

What I normally do is pour in 2 gallons of water then add 4 scoops of salt (1 scoop makes a gallon) and let it mix while I wait on my ro unit to make a couple more gallons. I’m wondering if the double concentration of salt is somehow affecting the calcium levels. Or if it dissolves back in once I add the other two gallons.

I’ll mix my batch tomorrow using the new salt and add all the water first to see if it makes any difference.

If not, I’ll look into my test kit and method of testing. Fun stuff lol

gbroadbridge · Jun 20, 2023

Thumbster said:
Well I got my scale today and it seems to be surprisingly accurate. I checked it several times with different weights and combined weights and it was dead on to the hundredth.

I also discovered my refractometer was only 1 ppt off. I mixed the solution to 35ppt and it was reading 34. That explains a small part of my low Ca but not the majority of it.

I did mix another couple gallons using the old salt and the Ca tested 360ppm. I’m going to mix a couple gallons from the new bucket tomorrow and measure it.

I’m also wondering if some of the calcium is precipitating out when I mix it. I usually mix about 4 gallons at a time using a bucket and a powerhead.

What I normally do is pour in 2 gallons of water then add 4 scoops of salt (1 scoop makes a gallon) and let it mix while I wait on my ro unit to make a couple more gallons. I’m wondering if the double concentration of salt is somehow affecting the calcium levels. Or if it dissolves back in once I add the other two gallons.

I’ll mix my batch tomorrow using the new salt and add all the water first to see if it makes any difference.

If not, I’ll look into my test kit and method of testing. Fun stuff lol

When mixing salt you should follow the directions given by the manufacturer.

In any event you should not be adding salt to less than about 90% of final volume of water as it is likely some precipitation will occur.

Also, you would normally not heat the solution until very close to final salinity For the same reason.

Thumbster · Jun 20, 2023

gbroadbridge said:
When mixing salt you should follow the directions given by the manufacturer.

In any event you should not be adding salt to less than about 90% of final volume of water as it is likely some precipitation will occur.

Also, you would normally not heat the solution until very close to final salinity For the same reason.

You may be absolutely correct but none of the things that you said are on the manufacturer directions. And it doesn’t say not to mix at higher concentrations and add water later.

I’m not trying to be argumentative, just pointing out the vagueness of the directions.

gbroadbridge · Jun 20, 2023

Thumbster said:
You may be absolutely correct but none of the things that you said are on the manufacturer directions. And it doesn’t say not to mix at higher concentrations and add water later.

I’m not trying to be argumentative, just pointing out the vagueness of the directions.

I'd suggest that the instructions tell you to use 1/2 cup per gallon of water.

They don't say to use 1 cup per gallon and then dilute later by addition of extra water.

So if you follow the instructions you will not have any unwanted precipitation.

I don't see how 'add 1/2 cup per gallon' is in any way vague

Thumbster · Jun 20, 2023

I guess we’re arguing then lol.

I read it as, for small quantities, the final concentration will be 1/2 cup per gallon of water.

Sisterlimonpot · Jun 21, 2023

I too always took the 1/2 cup per gallon to be a ballpark suggestion. I never relied on that to achieve proper salinity.

gbroadbridge · Jun 21, 2023

Sisterlimonpot said:
I too always took the 1/2 cup per gallon to be a ballpark suggestion. I never relied on that to achieve proper salinity.

Yes, but it's probably within 10% of what is needed, not 50% over.

Sisterlimonpot · Jun 21, 2023

I remember @Randy Holmes-Farley once posted about mixing salt to higher concentration in reference to precipitation, but I can't recall what he siad...