Disagree with above.
Many EI tanks are 50+ ppm nitrates for years.
Personally I routinely keep Rainbows for ten years with what most would consider high Nitrates.
If you set out to kill your fish with high Nitrates, you would be highly disappointed. Would take far more and longer than you think.
Now Discus is another thing entirely, but for most freshwater fish, Nitrates are of little concern.
At least that has been my experience in 40+ years of fish keeping.
Many EI tanks are 50+ ppm nitrates for years.
Personally I routinely keep Rainbows for ten years with what most would consider high Nitrates.
If you set out to kill your fish with high Nitrates, you would be highly disappointed. Would take far more and longer than you think.
Now Discus is another thing entirely, but for most freshwater fish, Nitrates are of little concern.
At least that has been my experience in 40+ years of fish keeping.