Nitrates will not go down

I would like to state that I am still pretty new to the saltwater life. I have a 46/50 gallon bow front tank (I know 46, but box stated 50) that has been running for almost a full year. Currently I have a yellow tang, hippo tang, 2 oscellaris clown, 2 damsels, one cleaner shrimp, two peppermint shrimp, 5 blue legged crabs, and a mix of 15 snails (3 turbo, 5 margarita, 7 astrea). I have done 10% water changes weekly and even tried twice a week, but still cannot get my nitrates down below 80. I only feed once a day mixing between frozen shrimp, seaweed, and garlic pellets. From the information I have read I do not believe that I am overstocked, but am starting to have my doubts. Any help or suggestions would be greatly appreciated.



The following is my current setup

46/50 gallon bow front

Lighting: dual T5's HO

Powerhead: 2 JVP-101 (800GPH)

HOB SKimmer: Corallife 65G (replacing soon with sump and overflow)

60 lbs of sand

75 lbs of LR (50ish is already LR, the other is added DR)

No Coral - They died :mad: Thoughts are the high nitrates.