I have a bunch of Umbrella Hairgrass (Eleocharis Vivipara) that I got about 2 weeks ago and half of it is turning yellow, I have a full spectrum led light on for 8.5 hours a day in a 10 gallon (6500K, 850 lumens, PAR is 72 at 12") no CO2, I use a fertilizer that has more than %3 of potassium once a week so I don't think it is a potassium deficiency. Is the light too low? Or is it just adjusting to my tank?