Is it normal for fish to live in water with a Ph of 9. I have a pair of golden wonder killifish, 4 ottos, and 2 borneo suckers. I know the killifish are tough. Should I be worried about this? The high Ph is a cause from new Eco-Complete. I started DIY Co2 and added PlantTabbs that make the water mildly acidic. I've also done W/C with RO and no buffers when I can. Hopefully this will help. I know the W/C hasn't helped.