Dear Maurice, you are very welcome here and I hope you get some good informations for your hobby. But Parosphromenus aquaristics is quite a bit more complicated and ambitious than normal aquaristics. Therefore you found that information on bacteria in a general forum for normal aquaristics using tap water. If you have a water nearly without any mineral content and a pH clearly in the acid sphere, things are different than from normal aquaria. There are, for instnace, other bacteria working than in harder water with a pH around 7.0.
So everything is quite in order, and you are welcome here to learn about an aquaristics outside of the normal hobby. But very interesting, opening a glimpse im the highly endangered world of the south-east Asian blackwater organisms adapted to extreme water conditions.