Sodium thiosulphate

[Fallout]

Hi

I have been trying to source a supply of dechlorinator that does nothing but
dechlorinate. According to my LFS the Tetra product only contains Sodium
thiosulphate, but the label says that it will also remove heavy metals.

Does Sodium thiosulphate remove metals as well as chlorine? As I mix my
plant food in with my change water and dechlorinator I think I may be making
the iron etc unavailable in the water column.

Any more info would be much appreciated.

- Jon

[David C. Stone]

In article >, Fallout >
wrote:

> Hi
>
> I have been trying to source a supply of dechlorinator that does nothing but
> dechlorinate. According to my LFS the Tetra product only contains Sodium
> thiosulphate, but the label says that it will also remove heavy metals.
>
> Does Sodium thiosulphate remove metals as well as chlorine? As I mix my
> plant food in with my change water and dechlorinator I think I may be making
> the iron etc unavailable in the water column.
>
> Any more info would be much appreciated.

Sodium thiosulphate (Na2S2O3) is a reducing agent that will convert
chlorine (Cl2) to chloride (Cl-). I can't see how it would remove heavy
metals - it does not, as far as I know, form stable metal-thiosulphate
complexes.

[Elaine T]

Fallout wrote:
> Hi
>
> I have been trying to source a supply of dechlorinator that does nothing but
> dechlorinate. According to my LFS the Tetra product only contains Sodium
> thiosulphate, but the label says that it will also remove heavy metals.
>
> Does Sodium thiosulphate remove metals as well as chlorine? As I mix my
> plant food in with my change water and dechlorinator I think I may be making
> the iron etc unavailable in the water column.
>
> Any more info would be much appreciated.
>
> - Jon
>
>
If you can find it, I believe Genesis is pure thiosulfate.

I've never had problems maintaining adequte iron for plants with water
treatments or even carbon or Chemi-pure. Are you seeing chlorosis?
Have you tested your iron levels to see whether you actually have a
problem? Iron in the water column must be chelated to stay in solution
so I doubt that it's available to react with heavy metal removers.

--
Elaine T __
http://eethomp.com/fish.html <'__><
rec.aquaria.* FAQ http://faq.thekrib.com

[Mean_Chlorine]

Thusly Elaine T > Spake Unto All:

<sodium thiosulfate>
As stated it should not form insoluble precipitates with iron,
although I have this faint recollection it may do so with lead,
mercury, and silver. I may be mistaken on that, though.

However... Have you considered using ascorbic acid (vitamin C) for
dechlorination?
One knifetip of ascorbic acid powder is sufficient to dechlorinate a
bucket of water, and ascorbic acid is cheap, easily available, works
also with chloramine, biodegradable, and non-toxic. It will drop the
pH a little, but normally not enough to be a problem.

[David C. Stone]

In article >, Mean_Chlorine
> wrote:

> <sodium thiosulfate>
> As stated it should not form insoluble precipitates with iron,
> although I have this faint recollection it may do so with lead,
> mercury, and silver. I may be mistaken on that, though.

That's possible if the thiosulphate disproportionates - it would form
sulphide as one product, which would give insoluble salts of the metal
cations you mention. I'm not sure to what extent that reaction would
occur at typical tank pH values, though - my inorganic text only notes
the reaction occurs "in acidic solutions"

[Fallout]

"David C. Stone" > wrote in message
...
> In article >, Fallout >
> wrote:
>
>> Hi
>>
>> I have been trying to source a supply of dechlorinator that does nothing
>> but
>> dechlorinate. According to my LFS the Tetra product only contains Sodium
>> thiosulphate, but the label says that it will also remove heavy metals.
>>
>> Does Sodium thiosulphate remove metals as well as chlorine? As I mix my
>> plant food in with my change water and dechlorinator I think I may be
>> making
>> the iron etc unavailable in the water column.
>>
>> Any more info would be much appreciated.
>
> Sodium thiosulphate (Na2S2O3) is a reducing agent that will convert
> chlorine (Cl2) to chloride (Cl-). I can't see how it would remove heavy
> metals - it does not, as far as I know, form stable metal-thiosulphate
> complexes.

Thanks, the product must have more in it than just dechlorinator then.

[Fallout]

"Elaine T" > wrote in message
m...
> Fallout wrote:
>> Hi
>>
>> I have been trying to source a supply of dechlorinator that does nothing
>> but dechlorinate. According to my LFS the Tetra product only contains
>> Sodium thiosulphate, but the label says that it will also remove heavy
>> metals.
>>
>> Does Sodium thiosulphate remove metals as well as chlorine? As I mix my
>> plant food in with my change water and dechlorinator I think I may be
>> making the iron etc unavailable in the water column.
>>
>> Any more info would be much appreciated.
>>
>> - Jon
> If you can find it, I believe Genesis is pure thiosulfate.
>
> I've never had problems maintaining adequte iron for plants with water
> treatments or even carbon or Chemi-pure. Are you seeing chlorosis? Have
> you tested your iron levels to see whether you actually have a problem?
> Iron in the water column must be chelated to stay in solution so I doubt
> that it's available to react with heavy metal removers.
>
> --
> Elaine T __
> http://eethomp.com/fish.html <'__><
> rec.aquaria.* FAQ http://faq.thekrib.com

I'm not seeing any signs of chlorosis, but I was wondering if I needed to
add ferts at all if it was being made unavailable to the plants in some
way. I am now adding the fert a few hours after the water change just in
case.

I do test for iron levels, but have only done so up til now just before a
weekly water change, at which point I can never see any trace. I guess I
probably need to dose more and test after the water change. Am I right in
thinking that a just detectable level of iron is about right?

Thanks - Jon

[Fallout]

"Mean_Chlorine" > wrote in message
...
> Thusly Elaine T > Spake Unto All:
>
> <sodium thiosulfate>
> As stated it should not form insoluble precipitates with iron,
> although I have this faint recollection it may do so with lead,
> mercury, and silver. I may be mistaken on that, though.
>
> However... Have you considered using ascorbic acid (vitamin C) for
> dechlorination?
> One knifetip of ascorbic acid powder is sufficient to dechlorinate a
> bucket of water, and ascorbic acid is cheap, easily available, works
> also with chloramine, biodegradable, and non-toxic. It will drop the
> pH a little, but normally not enough to be a problem.
>

That is great, so long as it doesn't drop the pH too much. I guess I shall
have to get some and try it. Thanks.

[Elaine T]

Fallout wrote:
> "Elaine T" > wrote in message
> m...
>
>>Fallout wrote:
>>
>>>Hi
>>>
>>>I have been trying to source a supply of dechlorinator that does nothing
>>>but dechlorinate. According to my LFS the Tetra product only contains
>>>Sodium thiosulphate, but the label says that it will also remove heavy
>>>metals.
>>>
>>>Does Sodium thiosulphate remove metals as well as chlorine? As I mix my
>>>plant food in with my change water and dechlorinator I think I may be
>>>making the iron etc unavailable in the water column.
>>>
>>>Any more info would be much appreciated.
>>>
>>>- Jon
>>
>>If you can find it, I believe Genesis is pure thiosulfate.
>>
>>I've never had problems maintaining adequte iron for plants with water
>>treatments or even carbon or Chemi-pure. Are you seeing chlorosis? Have
>>you tested your iron levels to see whether you actually have a problem?
>>Iron in the water column must be chelated to stay in solution so I doubt
>>that it's available to react with heavy metal removers.
>>
>>--
>>Elaine T __
>>http://eethomp.com/fish.html <'__><
>>rec.aquaria.* FAQ http://faq.thekrib.com
>
>
> I'm not seeing any signs of chlorosis, but I was wondering if I needed to
> add ferts at all if it was being made unavailable to the plants in some
> way. I am now adding the fert a few hours after the water change just in
> case.
>
> I do test for iron levels, but have only done so up til now just before a
> weekly water change, at which point I can never see any trace. I guess I
> probably need to dose more and test after the water change. Am I right in
> thinking that a just detectable level of iron is about right?
>
> Thanks - Jon
>
>
I don't know what your kit is, but many only measure free iron. Free
iron should be undetectable because it's toxic.

Chelated iron levels depend on the plant species, light level, growth
speed, and whether you have a laterite substrate. I shoot for 0.1 ppm
to 0.2 ppm of chelated iron in my slo-grow 2wpg tanks, but some plant
tanks need considerably more. Tom Bar recommends 0.1-0.2 ppm iron for a
plant tank that has iron (laterite, Flourite, etc.) in the substrate,
and 0.2-0.5 ppm for one that doesn't.

Many of us with plant tanks dose ferts and trace every other day. That
way, more is available to the plants as various fertilizers are used up
or precipitate out of solution.

--
Elaine T __
http://eethomp.com/fish.html <'__><
rec.aquaria.* FAQ http://faq.thekrib.com

[Dr Engelbert Buxbaum]

Fallout wrote:

> Hi
>
> I have been trying to source a supply of dechlorinator that does nothing but
> dechlorinate. According to my LFS the Tetra product only contains Sodium
> thiosulphate, but the label says that it will also remove heavy metals.

I am not sure how soluble iron thiosulphate is, but thiosulphate is used
only in tiny amounts (it catalyses the chemical conversion of
hypochloric acid) and is rather unstable, so it won't last long in a
tank. For both reasons I would not expect it to have a major effect on
iron concentration.

[Lord Don]

"Dr Engelbert Buxbaum" > wrote in message
...
> Fallout wrote:
>
>> Hi
>>
>> I have been trying to source a supply of dechlorinator that does nothing
>> but
>> dechlorinate. According to my LFS the Tetra product only contains Sodium
>> thiosulphate, but the label says that it will also remove heavy metals.
>
> I am not sure how soluble iron thiosulphate is, but thiosulphate is used
> only in tiny amounts (it catalyses the chemical conversion of
> hypochloric acid) and is rather unstable, so it won't last long in a
> tank. For both reasons I would not expect it to have a major effect on
> iron concentration.

If nasa can't remove heavy metals from their water I don't think a fish
tank chem can. It's a pretty lame claim as the tiny percentage these
products can remove is hardly going to impact anything but THE most delicate
marine organism ever for better or worse.
Just my take
If you want pure sodium thiosulphate why wouldn't you just get it from a
photography developement store?