Two part chemical sources

[ChrisH]

Thanks again for continued advice!

In the UK, supplies of sodium carbonate with any attachment of a 'food grade' label seem impossible to find. I have located one source, 'technical grade' given as 99.3% purity, with the following analysis:
Typical
Total Alkali Na2CO3 % : 99.00 MIN. 99.6
Total Alkali Na2O % : 57.90 MIN. 58.2
Bicarbonate N a H C O 3 % : 0.70 MAX. 0.21
Moisture (loss on heating ) % : 0.50 MAX. 0.20
Insolubles in water @ 20ºc. mg/kg : 200 MAX. 105
Chloride NaCl % : 0.30 MAX. 0.10
Sulphate Na2SO4 mg/kg : 400 MAX. 90
Iron Fe2O3 mg/kg : 30 MAX. 9
Fluoride F mg/kg : 15 MAX. <5*
Arsenic As mg/kg : 1 MAX. <0.1*
Cadmium Cd mg/kg : 1 MAX. <0.5*
Chromium Cr mg/kg : 1 MAX. <0.1*
Cobalt Co mg/kg : 1 MAX. <0.1*
Copper Cu mg/kg : 1 MAX. <0.1*
Lead Pb mg/kg : 1 MAX. <0.5*
Manganese Mn mg/kg : 1 MAX. <0.1*
Nickel Ni mg/kg : 1 MAX. <0.1*
Titanium Ti mg/kg : 1 MAX. <0.2*
Vanadium V mg/kg : 1 MAX. <0.1*
*Actual level is below the limit of detection

Is this pure enough? The impurites of copper, iron and so on make me nervous - okay, small amounts, but will presumably build up over time. There again, a food grade seems to have a definition of better than 99.5% so even that would have impurities, and so could the 'aquarium product' supplies.

Any thoughts in suitability, anyone?

 

[Dkeller_nc]

It doesn't look like what you've found actually has much, if any heavy metal impurities with the possible exception of iron, which will not cause any issues in a reef tank. You should be good.