Filter it and use it. If it becomes too ugly, or the pH becomes too low, dump it and replace it with one of these home-made solutions.
Chemicals can be purchased from: Dead Link Removed
1. Solution B
Sodium Sulfite, 65 grams - Sodium Metaborate, 20 grams
2. Borax 20 grams, for results "like that of D76"
Water to make, 1 liter
3. Or try Sodium Sulfite, 65 grams - Sodium Carbonate, 20 grams, Water to make, 1 liter
See: (there was a url link here which no longer exists)