New here. Major tank problems!!

[Heera]

Hi everyone,
Started my tank 6 months ago. here is what I have.
Hardware;
30 gallon FOWLR,
30lbs live rock, aragonite sand 2".
tunze 6205 - 600GPH, maxijet 1200. Coraline 65 skimmer
Marineland penguin 170 bio-wheel filter.

- a pair of percula clownfish
- 2 green chromis.
- 4 cerith snails, 4 nassarius snails.
- green pistol shrimp.

My tank been ok but have few major problems.
1. can't get the nitrite levels down from 15ppm.
2. My fish just stay in one area don't swim around the tank. When I turn powerheads off only than they swim around.

3. All the sudden last week my 1 chromis went blind. He was going up and down in the corner of the tank. Thank pacing and hitting tank sides. Still can't see food. I am so worried.

Please help on these issues and what else could I add to my stocking list.

Any input will be appreciated! Thanks in advance.

Heera.

 

[Heera]

Forgot about parameters;;
Ammonia, nitrite - 0
Nitrate -20
Salinity- 1.024
Temp- 78f
Ph. 7.8

 

[Grizz]

To much current? try aiming PH's at water surface How often do you feed and do water changes I run a 90g without a skimmer i do PWC's once a week 20g my trates never get above 5 ppm

 

[Heera]

Thanks for reply Grizz.
I have PH's at sides of the tank, pointed upwards towards center. PWC are done 20% bi-weekly. I do add top off water about a 1 liter everyday. Salinity stays around 1.0235 to 1.0245.