220 litre tank, set up since October. 1200 aqua one,and 1000 aqua one filters. 1200 filter set up since oct,other added January. Water changers 25% weekly with gravel clean too. fine Filter wool changed weekly and filter sponges rinse as needed, no more than, mthly. Ammonia 0 Nitrate a whoppin 50 on Nutrafin testing Nitrite 0.8 at least. What am I doing wrong. I'm guessing I'm have a mini cycle or something, but why. Am I cleaning gravel too much? Gonna do a big water change today. Cos I'm panicking.