Hi Guys, I'm new to the forum and new to fish keeping and I appologise in advance because I'm quite certain this question has been asked many times before. I have 126 litre fluval duo deep 800 tank which has been set up for just over 7 weeks. Approximately 1 month ago I bought 4 platys from my lfs as I was advised that they were hardy little fish who would help the cycle of the tank because they produced bacterias in thier gut. I did at this point not know ANYTHING about fishless cycling. After treating successfully fin rot, all seemed fine and my tank seemed to be going through the ammonia phase with ammonia peaking at no more than 0.50ppm [API test kit]. It seemed to drop for a couple of days and the nitrites kicked in, reading 0.25. I wasn't unduly worried but continued doing daliy water changes [10-15%], What I am worried about is my nitrite still. It has been at 0.5ppm for over 8 days now [that's 15 days in total of nitrite being detected in the tanks] and I am getting worried about my poor little platys. The Nitrite doesn't seem to be dropping AT ALL and I am still reading 0.25ppm Ammonia. Nitrate has been at 5ppm for the last 10days[previously reading 0] I have salt in the tank, maximum filtration and airation, daily water changes but I am wandering is there ANYTHING else I can be doing? Please help and many many thanks for any answers.