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Safe cleaning of Sodium Hypochlorite residue (sorry for the cock up)

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fuzzy:
A question for all you chemists out there-

I regularly change and clean injectors for a swimming pool dosing system. The chlorine injector is always very calcified with hardened deposits from the donor- Sodium Bisulphate.

What is a safe product to use to soften/ dissolve/ clean the deposits from the injectors please? I am sure the furious scraping with a screwdriver etc. is only providing a better key surface for the deposits top form.

Si S:
What's the chlorinating agent fuzzy?

fuzzy:
Sodium Bisulphate liquid supplied as a 10-11% strength.

The calcification occurs at the injector where the donor is introduced into the pool water pipework post filtration.

matthew:
Fuzzy, please confirm if this is Sodium Bisulphite (NaSO3) used in the water industry to reduce the chlorine in water after super chlorination for disinfection prior to entering supply or Sodium Bisulphate (NaHSO4)* which is used to adjust the pH of swimming pools and as a disinfection agent. There are subtle differences.

However in the hard water area we are in I suspect it makes little difference and what is being formed will be CaSO4 or gypsum and MgSO4 which are insoluble in water. I will leave it to a proper chemist to suggest what will dissolve these as I normally come across them as a byproduct I want to settle out.

*edited to correct mistake

caerau:
I presume you mean NaHSO4 for bisulphate as what you said (NaSO4) is not chemically feasible.


I would agree that it's likely limescale and so vinegar would work fine  - though on some sort of industrial scale it's probably quicker and cheaper to scrub.


I don't think the subtle differences between bisulfite and bisulphate are really important here as it's the calcium/magnersium that's likely causing the caking.  Both sodium bisulfite and sodium bisulphate are soluble in water and so washed off with water safely.


Bisulfite will be a fairly benign reducing agent and not really anything to worry about - they put it food (E222) as an antioxidant so it's not likely to be all that poisonous - whatever your views on E-numbers.  ;)

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