FYI: The recommended chemical for long term pickling and storage of Dessalator membranes is NOT Sodium metabisulfate (Na2S2O5) rather it is Sodium bisulfate (NaHSO4).
The long term storage solution should be 20% glycerin for freeze protection and 1% sodium bisulfate as a biocide.
They are VERY different chemicals with similar sounding names. Sodium metabisulfate is ONLY for short term cleaning of the membrane NOT storage.