i have a 55 gallon mixed tank that had been up and running for about 6 months or so w/o significant issue. I have been battling high nitrates, but everything (fish and coral) has seemed happy. In a foolish attempt to lower my nitrates I did about a 50% water change and it killed 5 snails, a crab, and my clam... I've never had issues in the past with changes, but this was a bigger water change than I normally do. It's been 3 days or so and everything still looks unhappy despite my nitrates being almost back up to where they were. What should I do next, I have a diy sulfur reactor I was going to start, but I don't know if I would help or hurt. Anybody have any experience with this or any insight into what my next step should be? I'm frraking out a little, I'm afraid this is he beginning of the end. Feel free to ask more about the tank if you have questions.