I have set up my first tropical fish tank, and currently have 1 Red Tailed Shark, 6 Neon Tetras, 4 Penguin Tetras, and 4 Silver Tip Tetras. The tank is 100l and has been set up for 4 months. I have done all the tests on the water, and it has settled in very well. Ammonia and Nitrate levels are...