I second this! Since we supplement Nitrate on a regular basis, we would have green water more often if, Nitrate were one of the causes. Since my tank has been established for a long time, the only time I get green water is if I get carried away uprooting to many plants at one time. It would be better to get your Nitrates below 20 ppm though.I've read that ammonia is one of the causes of green water. The other is too much light for too many hours.