Oh, wow - your R. macranda in the back is absolutely gorgeous, too! Is that R. macranda 'small-leaf' in the front? It looks so healthy! What are the tank specs? I'm particularly interested in what substrate you use.
Adding peat will take care of the acidic part initially, the long term result of any aquatic substrate will tend towards the neutral. Bacterial colonies take over and dominate the redox of a substrate after a couple of months.
That's why I add it. Amano's base substrates powersands have peat added although not a lot. Peat helps initial set ups and pH /redox is later dominated by bacterial and some plant root processes, not the substrate itself. That does not last long.