60 gallon cichlid tank water quality help!!

[Evo8]

OK so my water quality in my well established 60 gallon cichlid tank is all messed up..the parameters are all out of whack..I've tried everything to fix it and nothing has worked..any suggestions? I added a new filter about a month ago..could that do the Trick? The last few days my water has clouded as well.. probly about 15-16 fish in there

 

[severum mama]

What are the readings for ammonia, nitrite, and nitrate? What is your water change schedule? How long has the tank been set up? Any recent additions?

 

[Evo8]

Ammonia is at 0
Nitrite is at 1.0
Nitrate 20 ppm
PH 7.4/8 maybe

The tank it a few years old..although I recently redecorated adding sand and a new filter ( in addition to my original filter)