Here is a variant we'll call PCC based on work from Patrick Gainer that uses sodium carbonate in place of borax:
Sodium Carbonate - 7g
Ascorbic Acid - 6g
Phenidone - 0.15g
Water to make 1L
This is quite active so I thought it might be good for C-41 films that generally need a little extra "kick" when processed as black-and-white. Here is a frame from long expired Fuji Superia 400 @ EI400 developed for 8mins with normal agitation:
Processed as normal for me with no adjustments except re-size and JPEG conversion.
This should work for at least 12 rolls. My concern is buffer capacity of the sodium carbonate (this is another reason I like borax ... it's a really good buffer) so I'm thinking a bicarbonate/carbonate buffer may work better than straight carbonate and can be adjusted to bring the pH down to that of borax. I should be able to make this work with acetaminophen as well which uses tylenol + sodium hydroxide to make p-aminophenol instead of phenidone.