cardinal tetra dying

Hi everyone! I'm posting this again as the previous one seemed to disappear. Quick backstory: I'm quite new to fishkeeping, but I've made an effort to do everything correctly and I've done a lot of research on the right procedures. I have a ~30gal tank, and after it was fully cycled I added 6...

Hello Im really hoping someone can help me out. Im new to having an Aquarium and I have hit a serious snag. I attmpted a water only cycle for approx 6 weeks. I then purchased 12 cardinal tetra. After another 6 weeks to my delight all 12 were still with me. I'm religious on my weekly water...