My thoughts on new tank syndrome or mini cycle or a system that crashed give it time add the detoxifier change the water every third day to reduce ammonia levels I would stop screwing around with filters and adding or removing substrate until the tank is re cycled or fully cycled you could easily cause more damage or restart the process which will prolong the cycle. Looks like your on the right track good luck.
I used established filters to start the tank (and water, but that doesn't really matter) and the parameters were good, but I will admit I don't check them nearly often enough.