Response to pH questions

The activity of any developer tends to increase with its alkalinity (higher pH value), but I've never heard of, or seen, a table of 'optimum' pH value for a particular developing agent.
Most film developers have a pH of between 8.5 and 10 at their working strength.
All I can add is that both Metol and Glycin are regarded as soft working, low activity developers. Both will work with Sulphite alone as both the preservative and alkali, so I guess they're at their best at around pH 8.5 to 9.
When they're compounded with other developing agents, like Hydroquinone, that's a completely different matter.

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