I am having a myriad of issues cycling / starting my new tank.
Here's a short summary.
125 gallon freshwater.
2 Aqcua Clear 400 GPH
Originally had live plants. Have moved to just all artificial now.
Running for 6 weeks now
Ran for a few weeks fishless after setting up. After a few weeks added 2 common goldfish to help cycle. Both did fine for a week. Tank then underwent a bacteria bloom, got super cloudy and both died. Levels all spiked and remained high for a few weeks, never coming down, so decided to add API quick start. Levels all dropped to normal within days.
After tank had been set up for 4 weeks I continued treating with API quick start to keep levels normal, and added 3 silver dollars. Both developed red gills and fin rot and died within 2 days. Thinking tank still might not be cycled I waited another week and then added 10 Zebra Danio's since they are hardier. All died within 2 days after developing fin rot and red gills.
Let the tank sit another few weeks and tested water levels again. Everything was normal. This time added 2 goldfish again. Both did ok for a week, then seemed to develop white growth like bumps on them and redish gills; obviously both died.
So... at this point I am done killing fish. I clearly have a problem with my water and will not add anymore until this gets figured out.
My question for you is this: Is the likely cause of my problem that my tank is simply still not cycled after 6 weeks, or that I have a bacteria or fungal infection in my tank that needs to be treated?
Should I treat with medication for a week and then do a large (75-100%) water change since there are no fish or plants in it to worry about dying? Or do I just medicate and do small (10-20%) changes? Or do I not medicate and stop adding stuff to the water and just let it run for a few more weeks?