Salinity issue?

[Reef.]

Not sure if my refractometer is out or my salt parameters are off..

Anyone good with Maths?

I normally mix 38g of salt per liter which normally gives me exactly 1.026 salinity but noticed my alk was lower than it should be so it’s either the salt or my salinity is off, I’ve just read a thread where someone else had the same issue, turns out their salinity was off, someone posted to get the correct salinity (same salt as me) they mixed 41g per litre!!!

I mix 23litres at a time, anyone work out what the salinity would be using 38g as apposed to 41g? Would it make a noticeable difference?

 

[DC Reefer]

I think it would give you 1.024 - assuming that 41g is 1.026.

 

[Reef.]

I think it would give you 1.024 - assuming that 41g is 1.026.

oh great! I was thinking it might have been much lower so not panic territory.

Thanks for doing that, I should have paid more attention at school!

 

[DC Reefer]

NP - here is the math 38/41*.026+1=1.024.

 

[vetteguy53081]

You’re right on track

 

[Randy Holmes-Farley Verified Community Expert]

Just be sure to not try to translate that to other mixes. That exact amount of moisture in the ingredients impacts how much weight is need to attain any given salinity.

 

[Reef.]

Just be sure to not try to translate that to other mixes. That exact amount of moisture in the ingredients impacts how much weight is need to attain any given salinity.

I’ve tried to make your salinity solution, can’t get ahold of the Morton’s salt here in the UK, you mention table salt, I’ve tried one brand, had no luck, I guess all brands are not the same (Morton’s has sugar listed as an ingredient) I’ll try a couple of others, any tips on the best one to try? I didn’t realise salt had so many brands available.

 

[Randy Holmes-Farley Verified Community Expert]

I’ve tried to make your salinity solution, can’t get ahold of the Morton’s salt here in the UK, you mention table salt, I’ve tried one brand, had no luck, I guess all brands are not the same (Morton’s has sugar listed as an ingredient) I’ll try a couple of others, any tips on the best one to try? I didn’t realise salt had so many brands available.

If you can weigh it, any salt should be fine. The minor ingredients are not going to make much difference.

 

[nereefpat]

I'm a little confused.

Are we talking about trying to make a 1.026 salinity in the display, or are we trying to make the calibration solution out of table salt?

 

[Randy Holmes-Farley Verified Community Expert]

I'm a little confused.

Are we talking about trying to make a 1.026 salinity in the display, or are we trying to make the calibration solution out of table salt?

A calibration and/or reference solution for devices that cannot be calibrated.

 

[nereefpat]

Here is Randy's article, in case anyone missed it: http://www.reefkeeping.com/issues/2004-06/rhf/index.php

The short version, is you want to make a 36.5 grams per liter solution of table salt and water. That gives you a solution with the refractive index of 35 parts per thousand (1.026 s.g.) seawater.

 

[Reef.]

Ok I’ve ordered some new more precise scales, hopefully I can make this calibration fluid, I be already tried a few times, never worked, not sure if it was down to my previous scales.

 

[nereefpat]

Ok I’ve ordered some new more precise scales, hopefully I can make this calibration fluid, I be already tried a few times, never worked, not sure if it was down to my previous scales.

FYI, the bigger the batch you make, the less decimal places your scale will have to read.

 

[Reef.]

FYI, the bigger the batch you make, the less decimal places your scale will have to read.

yeah think that has been the issue, seems a couple of grains of salt is enough to throw off the accuracy off.

 

[Randy Holmes-Farley Verified Community Expert]

yeah think that has been the issue, seems a couple of grains of salt is enough to throw off the accuracy off.

How do you know it was off?

 

[Reef.]

How do you know it was off?

Because I tried a few times and with difference salts, none of them were anywhere near 35ppt, I even tried with my tank salt, so I’m guessing the scales were out or just not accurate enough.

 

[Randy Holmes-Farley Verified Community Expert]

Because I tried a few times and with difference salts, none of them were anywhere near 35ppt, I even tried with my tank salt, so I’m guessing the scales were out or just not accurate enough.

Tank salt will be WAY off and should not ever be used to make a standard. There is lots of variability in the moisture level.

I discuss the issue of precision and accuracy and some devices to use to weigh the salt here:

Salinity Checking … What To Trust …

What to trust… I bought a Hanna salinity checker in March. The Hanna works well, it tracks my old school refractometer nearly perfectly; as long it’s it’s calibrated. After the first few weeks of use it hold calibration well, usually a month or so. My experience is that in the first 2-3...

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