What caused the outbreak and how did you fix it?
My old 150-gallon tank was doing well until around April 2022, when it began to deteriorate rapidly (most of the pictures on the first page of this build thread were taken around this time). It was a slow burn, and the corals lost their color before succumbing to STN. Every coral in the tank was affected. I racked my brain to figure out what was causing it. I assumed it was my lighting, the Kalk I was using, high potassium levels, and so on. However, nothing I did should have resulted in the problems I encountered. Nothing I did made things better either.
After going through many logs trying to figure out what I did, I remembered that I had taken my UV offline in April because it was leaking and I was going to buy a larger one anyway for the new tank. This is when I began to suspect it was caused by bacteria or pathogens. I sent a sample to Aquabiomics, and the results showed that I had an extremely high level of Oceanospirillaceae bacteria.
Despite the high levels, Aquabiomics said my tank appeared to be healthy and did not have a reason as to why my system was going through this.
I did some research and discovered a link to a student thesis on Bacterial Communities in Healthy and Diseased Acropora cervicornis. I noticed in the paper that they found high levels of Oceanospirillaceae within the Gammaproteobacteria family or category in the diseased corals. These references were found on pages 47, 95, 96, and 102. It all started 3-4 weeks after I turned off my old UV, so it made sense that it could be a bacterial problem. I am convinced that my old UV was inhibiting a harmful pathogen or bacteria and that its removal allowed it to thrive.
I was talking with Mike Paletta about this and decided to use Ciprofloxacin. After just two weeks of using Cipro my corals completely turned around. I did not have any more STN, and color came back to all of the corals.
My filter socks bucket had a nasty black sludge at the bottom that I had never seen before. It looked like black paint. It appeared to be dead bacterial slough.
It resolved my low pH issue both during and after my dosage. My pH used to fluctuate between 7.8 and 7.99 on a daily basis. My pH rose to 8.16 at its peak during and after treatment. That is a significant pH increase.
pH levels during Cipro treatment
I know there has been a lot of talk recently about antibiotics and how harmful they are. However, I can say from personal experience that Cipro saved and revived my system.