As I said before, the emphasis on pH is probably misleading. As long as the print is well rinsed with plain water, selenium bath contains enough base to make the print alkaline rapidly.leicam5 said:
Also, the working capacity of selenium toner is limited by the amount of selenosulfate ion available for toning. At typical dilution of KRST, there is less than 1g/L of selenium and this is taken up by each print toned in the bath.
This is not a very good idea. There is no reason to use something that costs more, smells due to sulfur dioxide gas, and doesn't do anything better than other choices. Metabisulfite doesn't really have a good buffering power at pH 6 either.
That's misleadingly oversimplified. If unnecessary chemical is dumped, there is no question that no dumping is better. But we need to use some chemicals to achieve good photographic goal, while using fair effort to minimize potential hazard to the darkroom workers, the sewer system, environment, etc., and also to minimize wasted chemicals, water, and also costs of ingredients, disposal, transportation, etc. Selection of formula and ingredients are a trade-off among all these and other technical factors.
There is no use in overwashing prints. It not only give no advantage to the print's longevity, it wastes a lot of water.