We have 75 gallon tank that's been running for over a year. Last 7 months it has been a real struggle. Cut back light (fluval 3.0) to the point plants went backwoods its on right know at 50% at its peek and total of 7 hours. Cut back fish food to every 3 days but had to go back to every day because fish where getting skinny. Right know all traces of food are gone in 10 minutes or less. 2 months ago I started testing water parameters daily, never seen any ammonia, nitrite, have always struggled keeping nitrate levels above 20 and have to dose easy green twice a week at 8ml. Lots of pogo stem, 2 big Java ferns, Brazilian peny wort red darwf lilly. Have always fought hair algae, blue green slime ( marcine clears right up but comes back few week later) brown diatoms, then this week I saw black beard and decided to go nuclear and ordered a bunch of easy carbon. I know it's going to kill my vall, but don't recognize the name of what else it will kill. Any other ideas, we have 6 cherry barbs, 2 ottos, and white brushy nose pleco and those fish are fat with the buffet of algee.