Don't forget the need for adequate water circulation in order to get the CO2 and other nutrients supplied to all parts of the tank, all parts of all of the plants. Water circulation may well be the "missing link" that explains why some of us have algae blooming even with high CO2 per a drop checker, and high levels of all nutrients. Our success with growing plants is also our downfall. As the plants grow they increasingly block the water circulation. That leads to areas not having enough nutrients, especially CO2.