Sorry I could not put a name on the 'developer- stefan4u' of the thing I have come to call 'Flexicolor clone'.

I do recall all of the discussion when it's unveiling was ongoing here, maybe a few years ago.

I have the master file somewhere, but I only could find the striped down formula printed and held in a plastic sleeve in the front of my 'standard mixes' binder last night.

Ron, thanks for the tips on the fixer pH tuning.

BTW Ron, next time I am down your way do you have a use for a benchtop lab pH (and any other ion electrode) meter?
I picked up an Orion Research 901 microprocessor ion analyser, less instructions at an auction for a whole $2.
It appears to still be working properly, and is good to 0.1 mV, with differential double electrode inputs.
I am presently without electrodes to test it more fully.
It lets you set the intercept and positive or negative slope independently and thus display your measured ion (within the ISE probe range) directly on the digital readout.

I know the world has moved on to fancy offboard electrode preamps that feed a computer, but I could not ressit at the price.