# Sodium thiosulfate



## GraemeVW (10 Jul 2022)

I have been using this as dechlorinator but ive not really been that accurate. Not had any problems, but thought maybe I should work out the dosage better.

Does anyone know how?

I found this link...


			Jonah's Aquarium Sodium Thiosulfate Crystals Instructions
		


It suggests 4oz (100g) dissolved in almost 2 litres of water (I'd use deionised) would give me a solution that treats 1 us gallon with 1 drop of water.

The link suggests there are 100 drops in a teaspoon and a teaspoon treats 100 gallons.

I tend to treat 25 litres at a time, which I think works out to 7.5 drops.

Previously I'd just tipped a bit in, but I've been overdosing. Not caused me any problems though.

7.5 drops seems a tiny amount to add to 25 litres. I'm sure I read somewhere to double the dose if there is chloramine.

Anyone else use sodium thiosulfate?


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## Nick potts (10 Jul 2022)

Dosages are going to be very small. I haven't used it myself but found this.






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					www.intralabs.co.uk


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## GraemeVW (10 Jul 2022)

Thanks, your link says 0.1 to 0.2g per 10 litre.

When my migraine has subsided I'll do the maths and see how that works out to what I posted.


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## Vsevolod Stakhov (11 Jul 2022)

I have used sodium thiosulfate for a long time for chlorine removal. I dilute 18g of  Na2S2O3*5H2O (usually all available dry salts of this compound are pentahydrates) in 1l of water. 10ml of such a solution removes 1ppm of free chlorine in 100l of new water. I would also add that the shelf life of the solution is not endless (unlike dry salt) due to sulphurus bacteria decomposition, so it is a good idea to prepare solution for around a month or two and then replace it with a fresh one.

There is also some in-depth chemistry information in the Dave's article.


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## Parablennius (11 Jul 2022)

I just started using this after Prime ran out. I found this online. Screenshot of my particular mix for 100L W/C. I used the Prime 500ML bottle and dosing cap and added enough ST to match what I needed.


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## GraemeVW (11 Jul 2022)

So 17.5g in 500ml gives a solution where 5ml treats 100l?

Am i reading that right?

Thanks, very helpful. I ha e a few examples of dosing so I can work out if they all say about the same thing. Then I'll be a bit more confident in how little it needs!

I've been overdosing it hugely. I've read many reports saying overdosing is no problem at all, but also one or two that say you actually can over do it.


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## Aqua sobriquet (11 Jul 2022)

Is this for removing chloramine. I didn’t think it was used much in the UK, mainly the US?


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## dw1305 (11 Jul 2022)

Hi all,


Aqua sobriquet said:


> Is this for removing chloramine.


It will remove some chloramine at higher doses of sodium thiosulphate penthydrate (Na2S2O3.5H2O).  It actually liberates the ammonia during chlorine removal, so you are reliant on having enough oxygen, plants and / or microbial nitrification <"to remove the TAN">.

Water conditioners that "remove" chloramine work in a slightly strange  manner. Seachem won't tell what "Safe / Prime" contain, but the <"Aquarium Science"> link (which is really useful), says that "Prime" is sodium dithionite (Na2S2O4) and is no different in mode of action than sodium thiosulphate.  I don't know how he found this out, but I'd guess he is probably right.

He talks about sulphinate dechlorinators (where I thought "Prime" resided), and we do know their mode of action, because <"Amquel" has a patent">. There has been some debate about their actual action, and again <"the author suggests"> a certain amount of <"smoke and mirrors"> are deployed.


Aqua sobriquet said:


> I didn’t think it was used much in the UK, mainly the US?


Yes and no, more water companies are using it in the UK. the two circumstances it is used in are:

Where tap water takes a long time to reach the customer. In this case <"they should tell you">, and
where there is <"emergency chloramine dosing">, because the <"integrity of the water main is threatened">.
It is the latter case that has <"caused most of the problems">.

Part of the <"BREXIT bonus"> may be a relaxation of the water quality rules that we inherited from the EU. We are already seeing this with water companies being licensed to <"discharge untreated sewage"> into our rivers, and I'd <"probably predict"> that <"tap water quality"> will go the same way and we will end up <"like the USA"> with up to 5 ppm Cl2 in our tap water. 

cheers Darrel


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## Parablennius (11 Jul 2022)

GraemeVW said:


> So 17.5g in 500ml gives a solution where 5ml treats 100l?
> 
> Am i reading that right?
> 
> ...


Yes. Nees very little. That's what I'm using without incident although I do prepare change water the day before. I cribbed it off a Koi keepers forum.


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## Parablennius (11 Jul 2022)

Aqua sobriquet said:


> Is this for removing chloramine. I didn’t think it was used much in the UK, mainly the US?


I contacted United Utilities about this and they assure me they dose only chlorine.


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## GraemeVW (11 Jul 2022)

What water company?


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## GraemeVW (11 Jul 2022)

Ive been tryi to work out the maths from the 4 doses in this thread.
To treat 100l of water we seem to have suggestions of 0.17g, 0.18g, 0.66g and 1g of sodium thiosulfate.

That's quite a spread.

I think this is what puts people off using it, and why I ended up just mixing a solution of not very specific strength and just tipping some in! 

I'd quite like to get to a point where it feels like less of a guess, but still with a healthy margin of overdoing it.

Maybe I'll just stick to 1g per 100l.
I've seen reference to using 5x the dose to be sure, and 1g/100L if basically 5 times the lowest suggested dose.


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## GraemeVW (11 Jul 2022)

Deleted for now, rechecking my maths!


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## Aqua sobriquet (11 Jul 2022)

Parablennius said:


> I contacted United Utilities about this and they assure me they dose only chlorine.


I looked at the latest water quality report for my supply area and the only mention is Chlorine. 

When I used to use tap water I just drew off enough for a water change and ran an air stone in it for a while.


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## GraemeVW (11 Jul 2022)

I decided to use 1g per 100L.
So 25g, dissolved in 500ml of distilled water. 5ml of which treats a 25l drum.

It's more than some fish based folk say, but at the low end of what the suppliers say.


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## Parablennius (11 Jul 2022)

Aqua sobriquet said:


> I looked at the latest water quality report for my supply area and the only mention is Chlorine.
> 
> When I used to use tap water I just drew off enough for a water change and ran an air stone in it for a while.


I spoke with a lady at UU who assured me they don't use chloramine so I could probably let it gas off over night as I mineralise, heat and turnover via powerhead as I do now. I could get away with not using it but it's such a small dose, 5ml per 100L I may as well.


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## Parablennius (11 Jul 2022)

GraemeVW said:


> What water company?


United Utilites, very lucky, our lovely soft water comes mainly from the Cumbrian fells as far as I know.


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## _Maq_ (28 Jul 2022)

What about using activated carbon for dechlorination? Is it feasible in our conditions?


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## jaypeecee (28 Jul 2022)

_Maq_ said:


> What about using activated carbon for dechlorination? Is it feasible in our conditions?


Hi @_Maq_ 

As activated carbon (AC) normally relies on _ad_sorption, I would have thought that it wouldn't be very effective on ionic compounds. Unfortunately, my organic chemistry is somewhat 'frayed at the edges' these days. But, if we don't have anyone on UKAPS that can answer this question, it's one for David Bogert at Aquarium Science – The Science of Aquariums.

JPC


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## John q (28 Jul 2022)

_Maq_ said:


> What about using activated carbon for dechlorination? Is it feasible in our conditions?


Meaning in the regular tank filter? Then I'd say not, it would take time to remove the chlorine and exposing livestock to chlorine for any length of time isn't advisable.
I believe people use actived carbon filters to filter the water prior to putting it in the tank and that effectively removes any chlorine but to the best of my knowledge it doesn't remove chloramine.


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## _Maq_ (29 Jul 2022)

jaypeecee said:


> As activated carbon (AC) normally relies on _ad_sorption, I would have thought that it wouldn't be very effective on ionic compounds.


In this case, AC works as a catalyst.


John q said:


> to the best of my knowledge it doesn't remove chloramine.


It seems it does, it only takes a bit longer.
Chlorine and Chloramine Removal With Activated Carbon


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## ian_m (29 Jul 2022)

John q said:


> Meaning in the regular tank filter? Then I'd say not, it would take time to remove the chlorine and exposing livestock to chlorine for any length of time isn't advisable.
> I believe people use actived carbon filters to filter the water prior to putting it in the tank and that effectively removes any chlorine but to the best of my knowledge it doesn't remove chloramine.


A "dechlor" filter (activated carbon) will remove both chlorine and chloramine. However the flow rate has to be sufficiently slow to allow full absorption, as the chloramine is broken down to chlorine and ammonia and have to be absorbed by the filter.  Many people use these type filters before their RO systems to protect the RO membrane, as they are easily destroyed by chlorine and they won't remove ammonia. 
Lots of people use them to remove chlorine for fish water and drinking water use. You must make sure the filter is never exhausted, as after so many litres have flowed, as it will stop working.


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## _Maq_ (29 Jul 2022)

ian_m said:


> However the flow rate has to be sufficiently slow to allow full absorption, as the chloramine is broken down to chlorine and ammonia and have to be absorbed by the filter.


Yes, the flow speed seems to be the problem.
However, I think there's an imprecision in your post: Chloramine is broken down to chloride and ammonia, that's correct, but chlorine is then reduced to chloride (harmless). In the latter, AC works as a *catalyst*. In this, I believe AC exhaustion is only of minor importance.


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## ian_m (29 Jul 2022)

_Maq_ said:


> Yes, the flow speed seems to be the problem.
> However, I think there's an imprecision in your post: Chloramine is broken down to chloride and ammonia, that's correct, but chlorine is then reduced to chloride (harmless). In the latter, AC works as a *catalyst*. In this, I believe AC exhaustion is only of minor importance.


Sorry, you are correct, chloride comes out, which in a RO system is removed by the RO membrane.

Exhaustion is a problem, as it will allow chlorine and chloramine through when exhausted. When I had an evening tour of a local fish shop (closed down in pandemic and never recovered) they had a flow meter after the carbon filter (and before RO membrane) to work out when to change the carbon filter. (2000 gallons ?). All the RO went to storage containers and was tested for free chlorine and ammonia before being used in their tanks or sold to customers. Yes they has had positives for chlorine on RO output water as they had a failed carbon filter, possibly incorrect fitting or damaged during assembly. It wrecked the RO membrane and would have killed their fish and customers fish if it had been used.


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## jaypeecee (29 Jul 2022)

ian_m said:


> A "dechlor" filter (activated carbon) will remove both chlorine and chloramine.


Hi,

It's very rare that I need to remove chlorine and/or chloramine but it's good to know that it can be done by filtration.

I see that the _Dechlor_ filter can be obtained from the company, _Feedwater_.  A couple of days ago, I shortlisted this company for lab water tests. What is your experience of the services and products supplied by this company, if you don't mind my asking?

JPC


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## ian_m (1 Aug 2022)

jaypeecee said:


> A couple of days ago, I shortlisted this company for lab water tests. What is your experience of the services and products supplied by this company, if you don't mind my asking?


No experience. Just know that people use "dechlor" cartridges to remove chlorine and chloramine. I think you can actually used "plain olde activated carbon" to remove chlorine and chloramine, but flow rate has to be quite slow, to allow chloramine to be broken down and/or be absorbed successfully. The "dechlor" carbon cartridges have a catalyst (platinum ?) in them that greatly speeds up the process so you can get a higher flow rate.


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## jaypeecee (1 Aug 2022)

ian_m said:


> The "dechlor" carbon cartridges have a catalyst (platinum ?) in them that greatly speeds up the process so you can get a higher flow rate.


Hi @ian_m 

Thanks for your reply.

If the catalyst uses platinum, the cartridges are likely to be very expensive.

JPC


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## _Maq_ (1 Aug 2022)

jaypeecee said:


> If the catalyst uses platinum, the cartridges are likely to be very expensive.


Not necessarily. It's often the technology that makes things pricey more than microscopic amounts of precious materials.


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## jaypeecee (1 Aug 2022)

_Maq_ said:


> Not necessarily. It's often the technology that makes things pricey more than microscopic amounts of precious materials.


Hi @_Maq_ 

My background is in the electronics industry. I've worked with products that use gold, platinum, palladium, etc. The technology was simplicity itself but the material costs were very high. So, dependent on the product being manufactured, it can go one way or the other.

JPC


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