50% water change and still 20ppm nitrates

[naesco]

Milad when the equilibrium gets out of wack by overstocking overfeeding adding unecessary additives the tank goes wacko. This is even more the case in small tanks.

It is a newbie problem that we as newbies all faced.

If your ph is too low or your phospate is too high and you reach for a magic exilar to solve it it may be solved short term but the problem remains.

Test your water and let us know and you can make slow adjustments and with water changes will get your tank perfect. You will see.