Hi everyone,
Maurice, this is a beautiful story and you are defenitely at the right place, if you want to specialize. This is exactly the mentality we need!
So be welcome here.
Regarding your initial question, I made some observations that might be relevant.
I am running 3 paro tanks with black water of ec around 10 microsiemens/cm and ph around 5.
Also, I run another “normal” tank with a ph around 6.5 to 7 with pterophyllum scalare and some catfish (L333). In both tanks, I use catappa leaves to add the beneficial substances.
I always observed that the leaves in the normal tank vanished really quickly after only a matter of weeks. In the park tanks, this takes much longer. Sometimes the leaves are still intact after a month or so. Then they start to get muddy and slowly dissolve. If there is too much of a biotilm on them, I put them to the compost. If not I leave them. I usually thought of these differences as being caused by the L333 that would eat part of the leaves. I needed about twice the amount of leaves in the normal tank as opposed to the paros.
Now, sadly the L333 died probably because of their age. I had gotten them from a private breeder who sold me his old pairs. During the few months when I did not have any Catfish in my tank, I observed the same phenomenon. Actually, I feel the leaves are even quicker dissolved. I think that the L333 always fed on the biofilm on the leaves rather than the leave substance itself. So as a conclusion I would say that yes, the bacteria developpment slows rapidly in a lower oh environment but there are still bacteria active.