Nitrate Levels in Nano Cube

[zenway9]

I have a 12 gallon DX Nano cube. No matter how hard I try, I cannot get the nitrate levels under 10 ppm. I have done 3 water changes (3 gallons each time) in the past 2 weeks and no change. I have one Percula Clown and 5 snails and 8 blue hermits.
Is a level of 10 too high for a 12 gallon?

 

[bigarn]

There's nothing wrong with that reading ..... IMO if you can keep it 20 and lower it's fine.