Please help having trouble with Ammonia and Nitrite levels. I will try and keep it brief. Bought a Juwel Trigon 190 in January this year, set up the aquarium using the Juwel filter which came with the tank. Over the last 11 months I have slowly stocked up the tank with the following fish. 3 Cory Cats 2 Bristle Nose 8 Rummy Nose 15 Cardinal Tetras. Just added last week 6 juvenile Discus between 2.5” to 3” 2 weeks prior to getting the discus I thought I would do a bit of tank maintenance, I cleaned the filter media with tank water and gave the gravel a vac and topped the tank up with 50% fresh water, dechlorinated with Stress Coat. I only use tap, not gone for the RO option. Prior to adding the Discus I bought the Cardinal Tetras about 6 weeks ago. Over the last few days I lost a couple of Cardinals, so I checked the water and the Ammonia and Nitrite had risen, so carried out a 50% water change, checked daily and the Ammonia and Nitrite started to rise again, so carried out another water change, this time 75%. I’ve read that this could be down to using stress coat as the dechlorinator, as stress coat does not remove Chloramines, which could be giving me an incorrect reading of Ammonia and Nitrite So carried out another water change today but used Sachem Prime double dose as the dechlorinator. What else should I be doing. Water parameters prior to water change today: Ammonia 1mg/l Nitrite 1mg/l Nitrate 20mg/l Ph 7 Kh 120mg/l Gh 120mg/l After water change Ammonia 0 Nitrite 0 Nitrate 20mg/l Ph, Kh and Gh not changed.