Quote Originally Posted by StigHagen View Post
So you store it in 10% solution and then everytime you need to bleach you mix some of it to make a more dilute solution? The more dilute solution to you discard it after use or can it be saved for a prolonged time?

I have som very dilute solution I mixed a year ago and Im still using it. Is that a problem?
Most formulae suggest a 10% solution for storage, I do discard the 1% solution after use, but then I don't use excessive amounts.

If and when Ferricyanide decomposes it forms Prussian blue so starts to turn greenish, then blue, a 1% solution may keep OK for some time even when made up with tap water and there's a clear colour shift as it goes off.