Safe nitrate (NO3) level for Cardinal Tetras?

[Stu UK]

Hi everybody, I am new here having just returned to the hobby after a break of five years.

Anyway, my question is, what is a safe level of nitrate (NO3) for Cardinal Tetras before having to do a water change? Also, will NO3 levels continue to rise with the absence of plants or can they stabilise?

At the moment I have what I believe is a semi-cycled tank. Total ammonia is 0.25mg/l, NO2 is 0, NO3 is 10ppm. pH 7.0 and temp is 27 - 28c.

[dc88]

I have Cardinal Tetra in planted tank with NO3 usually between 10 to 20ppm with no problem at all. I add NO3 to fertelise the plant about 15ppm a week total.
I do water change weekly to keep it not to exceed 20ppm.
But this is with plants densely in the tank. If without plant I think theso sure the continue NO3 builtup could be faster.

[Stu UK]

Thank you for the very useful information. I don't have any live plants in my tank so I will be keeping an eye on the NO3. So far I haven't seen it rise above 10ppm though.