# Salt Meter



## dean (3 Feb 2021)

Hi Clever People
I’ve got some Ranchu goldfish coming and I need to measure the salt levels to keep it at 0.3% for the duration of the 4 week quarantine period. The easiest would be with a salt / salinity meter 

Can anyone recommend a brand or model ? 


Sent from my iPhone using Tapatalk


----------



## mort (4 Feb 2021)

I don't think most measure such low specific gravities as they are mostly aimed at the marine market. If you know the volume of the tank you should be able to work out how much salt to add and it won't go anywhere unless you do a water change. Again if you take water out, as long as you know how much you have removed, you can work out how much to add back in.
You can be quite accurate doing this and a slight swing either way shouldn't cause any problems, most people just seem to chuck a rough amount in and it seems to work.

You would need 3 grams per liter so a pair of reasonable scales is easier to find.


----------



## dw1305 (4 Feb 2021)

Hi all, 


mort said:


> You would need 3 grams per liter so a pair of reasonable scales is easier to find.


That one. It is a lot of salt.

cheers Darrel


----------



## dean (4 Feb 2021)

Hannah and lots of other manufacturers do low level salt meters 
They vary in price greatly from cheaper imports at less than £20 upto very expensive ones over £500 so was looking for recommendations 


Sent from my iPhone using Tapatalk


----------



## dw1305 (4 Feb 2021)

Hi all,


mort said:


> don't think most measure such low specific gravities





dean said:


> They vary in price greatly from cheaper imports at less than £20 upto very expensive ones over £500 so was looking for recommendations


It is sort of Apples & Pears again, what @mort  is saying is that most hydrometers or refractometers aren't going to work very well in a low specific gravity solution, but you can use a conductivity meter, which I assume are the meters you've been looking at? Because it is such a lot of salt any conductivity meter will do, including the £20 one.

Conductivity is a linear scale all the way from <"DI water to full strength seawater">.

I know 0.3% is quoted as the right amount of salt for Goldfish quarantine, but when I say it is a lot of salt, I really mean it.

If you want to use conductivity? The 1000 microS (1 milliS) conductivity standard solution is 491 mg/L NaCl.

I'm going to call 0.491g  "0.5g", so your 0.3% salt solution (3g in a litre) is ~ 6 miiliS = 6000 microS and ~3000 ppm TDS (you use 0.5 as the conversion factor when you know the salt is NaCl).

cheers Darrel


----------



## dean (12 Feb 2021)

While we’re on the subject of salt can anyone debunk a myth that’s been around years 

Is the anti cacking agent used in table salt bad for fish or is it just complete rubbish ?

For instance a well known brand sells “aquarium salt” which is sea salt, but it flows freely too 

Koi retailers sell salt by the sack and that brand of salt uses Sodium ferrocyanide as its anti cacking agent 

So they contradict each other !

I presume table salt or salt with any anti cacking agent in it is safe to use as the amount of the chemical (Sodium ferrocyanide) would be so small to cause any problems?


----------



## dw1305 (12 Feb 2021)

Hi all, 


dean said:


> Is the anti cacking agent used in table salt bad for fish or is it just complete rubbish ?


Yes, it is rubbish, the anti caking agents are either magnesium carbonate (MgCO3) or sodium hexaferrocyanide (Na4Fe(CN)6), but neither of the is very soluble, you can also ignore the iodized bit (should there be one), the amount of iodine added is neither here nor there.


> This has led to confusion with some people anxious about the safety of these additives because free cyanide and hydrogen cyanide are highly toxic. Hexacyanoferrates (or ferrocyanides) are not toxic; they are chemically-stable metal complexes and completely non-toxic. To make the point, one study gave rats a solution of 20,000 mg/L ferric ferrocyanide in drinking water for up to a total intake of 3,200 mg/kg (bw)/day for 12 weeks and the rats showed no signs of toxicity


From <"The great salt debate">.

Personally I'd be more concerned by keeping the fish in that salt concentration. 


dw1305 said:


> I'm going to call 0.491g "0.5g", so your 0.3% salt solution (3g in a litre) is ~ 6 miiliS = 6000 microS and ~3000 ppm TDS (you use 0.5 as the conversion factor when you know the salt is NaCl).



cheers Darrel


----------



## dean (12 Feb 2021)

0.3% is the starting point then it’s reduced with water changes 


Sent from my iPhone using Tapatalk


----------

