i just got my phos test kit yesterday! took a reading this morning - it's around 2ppm. I'm gonna have to read up on exactly what that means and where I wanna be and what to do about it.
UV light in freshwater? wow... this planted tank rabbit hole gets pretty deep, eh??
thanks for the comments!
Phosphates do not cause algae. That is not the problem. That is a good reading actually. PO4 is a necessary macro nutrient for plants.
You've got an imbalance like you said between light, co2 and fertz. Too much light could be the culprit. But I am not familiar with the LED fixture you have.
I had a persistent algae bloom in my tank and I couldn't figure out the cause and then I did. It was from excess nutrients; iron in my case. UV Sterilizer took care of it and never to return again after decreasing my Micro dosage.