Does anyone know how much the pH changes after developing 80 square inches (120 roll) of HP5 per liter of developer? The anti-halation dye makes it impossible to get a reading with pH papers, and I don't have a meter.

The reason for the question is that I have a project involving about 40 pieces of 8x20 film, and I'd like to concoct a replenisher that would let me develop about 10 sheets (successively) in my 3 liter capacity tray instead of having to dump it every sheet or two. (Developing multiple 8x20 sheets is out of the question... I cannot avoid scratching the film.)

I develop by inspection, so a small amount of activity loss is insignificant, but I suspect that the pH would get out of hand if I try to boost the developer with regular PC-TEA after each sheet or two. If the pH change is insignificant after developing a sheet, I might be able to use an Ascorbic acid/phenidone/propylene glycol booster to keep the developer capacity up without elevating the pH. But that's only speculation at this time.

Any ideas?