10X the desired level of phosphates has not been shown to lead to algae. Many of us have accidentally dosed that much without any consequence. BGA, cyanobacteria, seems to show up when you have too little nitrates, or when there is intense light, like sunlight on areas of the tank, or when there is very little water circulation in the tank. BBA suggests too much light for the amount of CO2 you have available to the plants. (Or any other shortage that stunts the plants growth.)