Hi Aleks
Large anaerobic bacteria colonies affect the pH along two pathways – release of carbon dioxide (CO2) and release of hydrogen ions (H+). Both processes lower the pH. I will have the bacteria in my DSB. My DSB consist of coral gravel (limestone) With start around 7.8 (in the gravel – not in the open water) –the lime will dissolve itself into two parts - Ca and CO3. The pH will adjust itself and the excess CO2 produced by the bacteria will be free to be used of the macro algae, zooxanthellae or aired out. I have a slow flow through the DSB and it will work like a slow calcium reactor – and I hope that it sooner or later will be enough lowering of the pH by natural processes – so I do not need to put in CO2 like in a normal calcium reactors. The lowering of the pH – that’s the effect I want in the DSB!
It is no coincidence that macro algae are above the DSB. They can use the excess carbon dioxide, released nutrients and minerals from the DSB
Sincerely Lasse