What level is Nitrate dangerous to fishes & corals

[MalaysiaBoleh]

My nitrate has risen to 20 ppm from 10 ppm last week. I have a 55 gallon tank with corals and fishes. My nitrate level used to be 10ppm consistently in the past and I added a few new fishes recently. Do I have to do with a water change? or is it acceptable?

[FuEl]

Think on the bright side..my nitrate is 50ppm.

[shiraz]

my nitrate was ever close to 100ppm before!

hmmmm PH dropped, created a sandstorm ###### nitrate attack!

nitrate at 10 and 20 is extremely good... but to get that level to zero, thats quite hard..

[williammuk]

Zero is ideal but tough to achieve. Your 20ppm is quite good already. Most hardy soft corals can do well even if NO3 is not zero. Don't worry too much about it ... unless you're keeping SPS?