Strange, the Tetenal (Jobo US) MSDS shows the Blix as:

Ingredients/Identity Information

AMMONIUM FERRIC EDTA (25-50%)
AMMONIUM THIOSULFATE (25-50%)
SODIUM SULFITE (5-10%)

It's a bit academic because I think Tetenal may have discontinued this kit some time ago, I may be wrong but I didn't see it on ther website last time I looked.

Ian