Responding on the TNC Lite. This is one of the best plant additives. It is low on the "hard" minerals like I said, calcium and magnesium, but your water is hard (the GH measures these two minerals primarily) and you will never be insufficient as long as you use the tap water either on its own with hard water fish species, or mixed with RO, there will still be sufficient calcium and magnesium for any plants. Second, there is no nitrogen or phosphorus in TNC Lite, but these should absolutely never be added to a fish tank that is not high-tech for plants. Plants use ammonia/ammonium as their nitrogen, and there is plenty of this produced by fish and the decomposition of organics. And phosphorus is high enough in fish foods to provide more than what any plants will need in such a tank.
As for black beard/brush algae...problem algae is caused by an imbalance in the light/nutrients. Period. The aquarist has to balance or rebalance things and problem solved. Each change in one factor can take a couple weeks before the effects are seen. We begin with a reasonable balance and work from there, tweaking as needed. I had brush algae in some tanks on and off for years, but once I finally sorted out the light and nutrient balance, my tanks, all 8 of them, remained problem-algae free for 8 years.
