Nitrates will not go down.

I have 12 fish... Most small Goby...2 clowns.... Atlantic Blue Tang, Blue hippo...and 3 bassets...I also have 4 shrimp, and a pistol shrimp.

I feed a cube in the morning and evening

found this above lol

 

one cube a day is plenty, make sure to rinse cube in fine mesh net prior to putting into tank. I would advise your next water change to be 50% new water. that should take your nitrates down to 20ppm. also introducing a ball of cheato into the mix would help with lowering nitrates.

 

Ok tanks been up for 11 months my question is what kind of rock did you put in was it live i had a problem when i put live rock in my tank it just leached out nitrates i did everything took rock out shook my rock out in a bucket of my old water and they dropped, now i buy all dry i learned my lesson

 

I second that you are feeding too much, i would feed one cube a day, and put it in a bit at a time, not all at once. This will give the fish more chances to get the food before it blows around and lodges somewhere to rot.

Just for perspective i have 7 fish and only feed a 1/2 cube every 2 days.