I've had these plants in this tank for about 10 months. Haven't added anything new lately at all. In fact, I'm on strike where I work, so I have actually been doing 2 50% water changes a week. Ammonia and Nitrite are always 0, and Nitrate is always 10 or less. Other specs are in my signature. I add Flourish once a week, Flourish Potassium 2 times a week, 15ml of Flourish Excel with 15 gallon water change once a week, and 10ml Flourish Excel in the middle of the week. I have'nt had any bad algae for over a year, so this one is a surprise. I have had BBA BGA and staghorn algae, and this looks nothing like those to me. Any Ideas?