Hi, I set up a 5.5 gallon rectangular tank, with a filter for a 10 gallon tank. I put 5 neon tetras in it, then 5 ghost shrimp. Over the course of 3-4 days, all of the ghost shrimp died. I got an oto. 2 days and it died. The neons continued to seem fine. I had my water tested and it was high in...