dougg
Well-Known Member
Where are you buying descent size quantities of Sodium metabisulphate from>
Sodium Metabisulphate
- Thread starter dougg
- Start date
NUTMEG
Well-Known Member
I'm not.
I used to when I ran a small cider company. Used to buy it from Vigo Vineyard Supplies in Somerset.
Not a lot of use on a boat though, or am I missing something?
I used to when I ran a small cider company. Used to buy it from Vigo Vineyard Supplies in Somerset.
Not a lot of use on a boat though, or am I missing something?
VicS
Well-Known Member
I think you probably mean sodium metabisulphite
What sort of quanity do you need and what are you using it for.
Any winemaking suppliers should have it, or potassium metabisulphite, in 250g or 500g jars or similar
Last edited:
dougg
Well-Known Member
Yes thats the stuff!!
Im going to use the watermaker this season, not used one before. I dont have any idea how much i will need for say a 6 month cruise, maybe some one could enlighten me.
Im going to use the watermaker this season, not used one before. I dont have any idea how much i will need for say a 6 month cruise, maybe some one could enlighten me.
Gargleblaster
Well-Known Member
I used to buy Sodium Metabisulphite from Wilkinsons for a small plastic container that would last me 5 years it cost 58p. Noticed last time I went to buy it the cost was about £3.50 and it was called beer cleaning powder or something like that.
Marsupial
Well-Known Member
you can use either sulphite or sulphate the water maker wont mind they will both do the same job. I buy mine on ebay
http://www.ebay.co.uk/itm/1kg-Sodiu...Equipment_Lab_Supplies_ET&hash=item4aad2b9a72
the same suppliers can aslo provide citric acid and sodium hydroxide - (drain cleaner) the two cleaning solutions used for membranes.
how much you need depends on the volume of the system, the idea is to use the sodium metabisulphate at the end of the season to pickle the membrane, or if the membrane will be unused for over a week or so. The pickle solution acts as a barrier to prevent bacterial growth, its the sulphur that does the work, it denies anything living access to oxygen so it dies. If the water maker is in constant use - which is what they like - then you wont need much pickling solution.
Last edited:
VicS
Well-Known Member
Surely it is sodium metabisulphite that is required. It is used as a source of sulphur dioxide which is what sterilises the membrane and prevents bacterial growth.
Sodium sulphate will do nothing useful in this respect.
Marsupial
Well-Known Member
Vic sodium metabisuphate not sodium sulphate!
the difference between sodium metabisulphite and sodium metabisulphate is not worth considering if all you are using for is to prevent bactierial growth in RO membranes either will work, sorry if I did nt make that clear.
the difference between sodium metabisulphite and sodium metabisulphate is not worth considering if all you are using for is to prevent bactierial growth in RO membranes either will work, sorry if I did nt make that clear.
VicS
Well-Known Member
Oh and what on earth is sodium metabisulphate
Sodium metabisulphite is Na2S2O5
what is the formula of sodium metabisulpate?
chasroberts
Well-Known Member
Google says Sodium Metabisulphate is Na2S2O5 as well. I'm confused......
A
angelsson
Guest
Can it be used in water tanks for cleansing?
VicS
Well-Known Member
Marsupial
Well-Known Member
technically the sulphate version has one more oxygen atom than sulphite which in turn should have one more oxygen atom than a sulphide, but all the suppliers seem to give the same formula whether its sulphide, sulphite or sulphate so I too am a little confused, but the good news is its not a show stopper - they all work.
VicS
Well-Known Member
I am afraid you have all this seriously muddled up
What you need, as source of sulphur dioxide for sterilising your watermaker membrane, is sodium metabisulphite Na2S2O5.
There is, to the best of my knowledge, no such thing as sodium metabisulphate . Anything so described or labelled is incorrectly labelled or described.
Sodium sulphate is Na2SO4
Sodium bisulphate, aka sodium hydrogen sulphate, is NaHSO4. It is strongly acidic and was at one time I believe used in lavatory cleaners
Sodium sulphite is Na2SO3. It will produce SO2 when treated with dilute acid and warmed.
Another common chemical is sodium thiosulphate Na2S2O3. It is/was used in the processing of photographic film and paper
Sodium sulphide is Na2S. That produces evil smelling hydrogen sulphide if treated with dilute acid and even on exposure to moist air. You wont be wanting to treat your membrane with that.
Last edited:
