The answer is somewhat ...

The answer is somewhat complex and varies with operations.  We have a patented product that is a blend with carbohydrazide and we have a simple way in which we feed it and I'd assume you could use this same method. We start the feed at 10 times the DO content. So 10ppb DO, the starting feed would be 100ppb of our product.  We then monitor Fe and Cu levels.  Once these drop to ND, we will lower the feed of the product by 10% every 3 weeks until Fe or Cu values rise to detectible. Then we increase it 5%.  The only reason you are feeding the scavenger is to stop the corrosion and not seeing either metal would indicate you have stopped corrosion. Dosage doesn't tell you what your system needs, you system will tell you. Hope this helps.