Where are the Nitrates coming from?

[RaymondL]

Started one tank at the end of August this year and it cycle end of September - It's a 15 gallon cube. I am using Caribsea aragonite substrate and new macro rock. I changed 50% of the water after cycling.

2 few weeks after cycling I added a pair of clowns and 2 Nassarius snails a month later. Nitrate level is at 12ppm, and I brought it down from 20ppm after a water change earlier this week. Today I tested the Nitrates and they are back up to 18ppm.

Where are the nitrates coming from? For one, I am not overfeeding - I"m very mindful of that. I am also running a skimmer as well in hopes to keep the levels low. But with 2 clowns and some snails, what could possibly be generating the nitrates? Is it because the tank is still new??

Thoughts please.
Thanks

 

[I never finish anythi]

What source of water do you use ??

 

[RaymondL]

What source of water do you use ??

I purchased a 4 stage RODI unit, so am using that

 

[I never finish anythi]

What about filtration?? Import/export . How much do you feed the clowns and what do you feed them ?