My tank started to go real murky, so I stopped feeding my fish checked the filters ( I have one 30 gal filter and one 70 gal filter in a 55 gal tank) they are fine, so I did a water change and left it for a day and a bit and now it has started to turn a green colour and is even more murky, I'm thinking I have to many fish, I am new to this scene so pls let me know I have a lemon oscar about 6 1\2 inches a snakehead about 7 inches, peacock chiclid, and a blue ahli, the latter two are leaving the tank soon, o ya an algae eater about 8 inches, I have now taken the rock out and am about to do another water change, is there anything else I can do?