Now I am seriously confused. I am new to this, my tank (125 gallon) is about six weeks old. I have no fish, a mushroom toadstool, two zoanthid colonies, two torches, a duncan, a small GSP, three shrimp, six emerald crabs, and two sea hares. I am experiencing a major hair/string algae outbreak (hence I got the crabs and the hares). I consistently measure ammonia 1-2x weekly for the past few weeks and it is always ZERO. Nitrates are around 15. How can there be ammonia fueling such growth if I can't read it? And in the end are you just saying clean my tank?