New (to me) toy- conductivity meter

[rishma]

I’m just excited and nobody outside this forum would care

 

[Randy Holmes-Farley Verified Community Expert]

Nice!

Is that a tank value? Did you calibrate it? How?

 

[rishma]

Nice!

Is that a tank value? Did you calibrate it? How?

Did not calibrate yet. plan to make your DIY Morton salt solution. I just turned it on to see if it worked. That is my tank value, close enough to what I expected to be excited about my eBay purchase. I think it works!

I noticed in my kitchen cabinet I have Morton’s iodized sea salt. I should buy regular iodized salt to make the calibration solution, right??

 

[Randy Holmes-Farley Verified Community Expert]

Did not calibrate yet. plan to make your DIY Morton salt solution. I just turned it on to see if it worked. That is my tank value, close enough to what I expected to be excited about my eBay purchase. I think it works!

I noticed in my kitchen cabinet I have Morton’s iodized sea salt. I should buy regular iodized salt to make the calibration solution, right??

Probably no important difference since I think there's really not much else is sea salt at levels that would impact the result, but I'd use regular salt (iodized or not), and if you wan to be very careful, give it a bake before weighing it to remove any water that might be there. I did not bother, since it does not form any solid hydrates, it would just be moisture on the salt grain surfaces.

 

[rishma]

Probably no important difference since I think there's really not much else is sea salt at levels that would impact the result, but I'd use regular salt (iodized or not), and if you wan to be very careful, give it a bake before weighing it to remove any water that might be there. I did not bother, since it does not form any solid hydrates, it would just be moisture on the salt grain surfaces.

I’ll get some regular and bake it.

Funny story, I baked some magnesium salts a few weeks ago because they absorbed humidity and clumped. You can guess what happened

 

[Randy Holmes-Farley Verified Community Expert]

I’ll get some regular and bake it.

Funny story, I baked some magnesium salts a few weeks ago because they absorbed humidity and clumped. You can guess what happened

Never tried. Did it liquify?

 

[rishma]

Never tried. Did it liquify?

Yes. I opened then oven and had liquid salt!!! But it was not clumpy anymore

 

[Randy Holmes-Farley Verified Community Expert]

Yes. I opened then oven and had liquid salt!!! But it was not clumpy anymore

lol at least it didn’t pop like popcorn splattering everywhere. lol

 

[Randy Holmes-Farley Verified Community Expert]

You inspired me to measure my salinity. 35.5 ppt. I’m happy with that. :)

 

[rishma]

You inspires me to measure my salinity. 35.5 ppt. I’m happy with that. :)

I was not sure how to convert so googled it and came up with 35ppt. I’ll have to find a more precise conversion. Though I could just shoot for 53ms/cm

 

[Randy Holmes-Farley Verified Community Expert]

I was not sure how to convert so googled it and came up with 35ppt. I’ll have to find a more precise conversion. Though I could just shoot for 53ms/cm

I think it is plenty accurate to use 53 mS/cm = 35 ppt and scale it up or down linearly.

So 50 mS/cm = 50/53 x 35 ppt = 33.0 ppt

 

[Kazumi]

sorry, I misread Randy's post. I edited my original post

 

[rishma]

Well, the DIY conductivity standard was not very satisfying. I feel my scale might not be accurate enough.

I made it 4 times. Measuring the salt was likely the issue. It seems like I’d add some salt to the scale and it wouldn’t respond if the amount added was very small.

First 2 standards:
54.86
51.89
Not good…

In the first two I was adding salt and water to glassware. The scales max is 500 grams so I decided maybe tare with the 175 g glass was making the measurements off. I remade the standard 2x with some very light disposable plastic cups. (I did not bake the salt for standards 3 and 4.

#3 and #4
52.67
52.43

Better, maybe even good enough. But I’m doubting my standards after the first 2 tries so I’ll make some more until I’m showing better precision.

The water weight and volumes lined up, so I think salt is the variable.

I think it is plenty accurate to use 53 mS/cm = 35 ppt and scale it up or down linearly.

So 50 mS/cm = 50/53 x 35 ppt = 33.0 ppt

 

[Randy Holmes-Farley Verified Community Expert]

What precision does your scale have? Mine reads to 0.01 g. I would not rely on 35.00 being different than 35.02, but I got some weight standards from Amazon for not much cost, and it is certainly accurate with those weights.

 

[rishma]

What precision does your scale have?

0.01

 

[rishma]

When I baked the salt at 300F for 30 min it had a slight brown tint. Maybe not an issue but I didn’t like that

 

[rishma]

What precision does your scale have? Mine reads to 0.01 g. I would not rely on 35.00 being different than 35.02, but I got some weight standards from Amazon for not much cost, and it is certainly accurate with those weights.

For about the same price I can get a 50g scale with 0.001.

 

[Randy Holmes-Farley Verified Community Expert]

This set of weights to check the scale is only $10.

https://a.co/d/gsd4Su8

 

[Randy Holmes-Farley Verified Community Expert]

When I baked the salt at 300F for 30 min it had a slight brown tint. Maybe not an issue but I didn’t like that

Might be some organics in it that browned. Morton's lists some dextrose. That would do it.

 

[rishma]

I bought a scale that reads done to 0.001 g and some calibration weights. I made two back to back standards with 12.400g salt and 364.00g water. They are within 0.2% of each other so I mixed them together and calibrated the unit.

I am now mixing a saturated kalkwasser standard. I have a magnetic stirrer and I’m measuring periodically to see how long it takes to saturate. I have a feeling I have not been mixing kalk long enough for 30 years. I may start a separate thread on this.