I actually keep my apistogramma is blackwater. I have began to play with it a lot. It really makes the colors pop. I use mainly almond leaves I keep a bucket ( it’s a smaller tank than yours) with them soaking for water changes and top offs. A lot of people will use moss in their filter as well to maintain the tannins. I’m interested to know where you sourced alder cones locally if you don’t mind me asking. Birch cones can also be used instead of alder cones.