please help with 14 g nano tank

[hibort2]

i been having a problem with my nitrate i just did a 4 gallon water change ph is fine i am using r/o water and i tested the r/o water before putting into the tank. the test was 0 tested the water after the water change and the nitrates were about 20 ppm the same as before the water change. i been doing water changes for the last few weeks about 3 -4 gallons at a time ??????? i dont have bio balls , i used crushed rock , i dont have a skimmer i use the nano filter and the sponge right before the return witch the filter was replaced and the sponge was cleaned out dont know what to do can any one help

 

[aznt1217]

Could be your substrate. Could be a old test kit.

Maybe you need a better clean up crew as well.

 

[DHaut]

Need lots more info:

How old is the tank, what do you have in it? How much do you feed?

The crushed rock works much like bioballs - they're unnecessary as well. Look into refugium mods for that chamber instead. Growing chaeto is much better than having balls or rocks back there.