I assumed that you were using a powdered fixer mix, sorry. I use a concentrated liquid fixer as well (in my case, TF-4) and do as Wigwam has suggested. I mix the working strength fixer from the concetrated fixer one liter at a time (or three in my case, one for film, one for 1st paper fix, and 1 for second paper fix) and store it in 1 liter containers. Each time I use the working liter, I put it back into it's container until it is time for it to be replaced. Sorry about the confusion, but so many people seem to be using powdered fixers these days I assumed incorrectly.
- Randy