It is probably your phosphates that are causing the algae bloom. You should test your phosphate. I would bet that they are at least 0.5 ppm
. You shpould also test more than phosphate and nitrate. Test ammonia, phosphate, nitrite, and nitrate. Test these every time you run a test. If your phosphate test positive with what ever the ppm
may be, this would mean that you are only in stage two of the nitrogen cycle. If you do not understand the nitrogen cycle let me know and i will explain in depth. It would be pointless for me to explain it if you already know. If you don't pm me or i can post it within the thread. It is not odd at all that your nitrate is 0 ppm
. This is because you have not completed the cycle yet, which means you are either in stage 1, 2, or 3. The reason I think you are in stage two is because of the algae. Phosphates feed algae and encourage the growth along with your lights. But your lights are not the problem. So test those four things and let us know the results. I will give more info. from there.