QT Everything in the tank 15 gallon Penguin 100 bio wheel Maxi-Jet 600 (160 gph) heater RO water Red Sea Salt 1.025 sg temp - 80 degrees Cycled tank with a couple of shrimp. Tank cycled like it should. However, the Nitrates were still at 180 after Ammonia and Nitrites were 0. pH was also low at 7.4. I did a 15% water change yesterday to bring the Nitrates down. However, that has not done any good and my other levels have spiked. Ammonia - .25 Nitrites - .25 Nitrates - 180 pH - 7.8 Before I did the water change Ammonia and Nitrites were 0 and Nitrates were at 180 and pH was at 7.4. Why would a water change cause a spike in Ammonia and Nitrates. I added nothing but RO water with salt at 1.025.