For me personally, in a low tech tank, I have never had BBA even appear. I keep a nice flow in the tank, not too powerful and with the low lights, usually the fish respiration seems to be enough for slow growth, but I sometimes add excel(if I have the extra money to spend) to my low tech tanks just to provide that liquid carbon source along with "Root tabs" as my substrate fertilizer. I test nitrates once a week and if I need to, I add flourish nitrogen or something, but for the most part, the fish waste, and respiration along with the plants keeps a nice balance and I think that's the important part. Balance. Keep a healthy amount of plants and don't overdo it on the number of fish. To be honest, I don't use any fertilizers in my low tech tanks beyond the flourish root tabs in the substrate and that seems to be fine. I never really see any nutritional deficiencies and when I test my water, if I find I am running low on nitrates, I add nitrogen. Maybe I am just lucky, but until I went high tech, I never experienced BBA....