I've mixed up (according to an older formula) a developer using Metol, HQ, sodium carbonate, sodium sulphite, borax and potassium bromide. A couple of liters. Then, per instructions, I mixed up a liter of replenisher, which is the same formulat minus the potassium bromide (because in use the re-used main developer will pick up bromide from the developing process). Interestingly, the two liters of primary developer are still quite clear, i.e, not brownish, after about three months and repeated use. The replenisher, mixed at the same time, is now relatively brown which indicates oxidation AFAIK. Each is in a fully stoppered bottle, and each bottle does have some air in it, relatively equal amounts relative to the surface area of liquid exposed. Air tight, light tight. Same storage conditions. So -- should I conclude that potassium bromide in a formula inhibits oxidation? Secondarily, do you think the brownish replenisher can still be used or should I toss it and mix up fresh? I usually take 30ml out of the main developer and add in 30ml of the replenisher for each roll or two run through. All thoughts welcome!