I was just informed today that I shouldn't have any Nitrates in my tank, it should be zero, here I have had my tank for over a year without any problems, the Nitrates would be between 20-40. Now I am going to strive to get it to 0. Does anyone know about this? My tank is currently at 10
thanks

Nitrates should not be at zero your level is fine. It is the Nitrites and ammonia at zero and if not more water changes are necessary. Whoever told you that nitrates should be at zero does not know about cycled tanks or was misinformed.

thank you for your reply, I bought a cory catfish today, I couldn't understand why my last catfish died, it was a green cory, and thats when they said that I shouldn't have any nitrates at all, so it confused me, I have been keeping my Nitrates between 10-20 with water changes every week to sometimes twice a week. then how much nitrate is too high? my understanding was not to get it over 100, what happens if you don't have any nitrates?? thanks so much

Nitrates should remain below 40 - this is a healthy amount.

If you don't have any nitrates, it could just mean that a tank isn't cycled. When a tank cycles, ammonia is converted to nitrites and then nitrites to nitrates - which will then give you a reading.

Your catfish may have passed due to another reason - certainly not from high nitrates in your tank as they are well and truly in the safe range

thank you so much! I thought I killed him! I hate losing any of my babies, I felt terrible when it happened. You have made me feel so much better
Are all cory cats just as hardy as these other, meaning, green, spotted and albino? The one that died was a green, just over night it happened.
Thanks again you guys, I would be lost without this post