I've started my AP system on the 4th of September - the system is still cycling (with fish- tilapia). I've had a difficult time keeping my pH down, it's around 7.6 - 7.8. I've been using muriatic acid daily in very small amounts but maybe I should increase the application? Nitrite levels started climbing late last week and are above 5ppm (my test kit stops at 5 so I'm not sure how high the nitrit…