A low ph is something that you want, to replicate black water conditions. South American blackwater areas have a low ph. The water is also tinted brown from tanins. So the driftwood leaching tanins into the water is something you want in terms of staining the water and keeping the ph low. Dead oak leaves, or indian almond leaves will also serve to soften your water and release tanins. This will also give your tank a more authentic blackwater look. Black water is dark, lighting should be subdued so expect that to be part of the true blackwater aesthetic. Black background works best, or no background at all. Another option is brown, but that's really about all that would work. Good luck!