Planted tanks are a lot of work. It is hard to balance light and nutrients and keep algae at bay. I had a sudden die back of plants, water tested fine, fish doing great....then I decided it was too much algae. I cut back on light and it helped, but I still had algae. I transferred about 25 cherry shrimp over from another tank and a few days later algae was gone! I couldn't believe how well they cleaned it up. I have used medications for disease, but for the columnaris I successfully got rid of it with salt in quarantine tank and daily partial water changes. I had 2 types of medicated food and also tried medications that you add to the water. It didn't budge until I started changing water daily. Once it was cleared up I just gradually cut back the water changes.