Do you need more than 20ml? Something closer to 40ml? We may be able to help! Let me know by emailing me email@example.com.
Also, what do you think the minimum volume would be that could accommodate a pH probe?
Or, better still, a standard 12 mm diameter ion selective electrode?
Combination probes are available that can measure pH, ORP, conductivity & T, all in one 12 mm probe.
I’ve sent an email as well - would definitely be interested in a larger volume Pioreactor.