Have you tested your tap water parameters? Not sure if anyone has asked or if you said you did, could it be small amounts if ammonia in the tap? Try doing wc once a week see if it clears up, do your nitrates really go so high that you feel the need to do so many water changes, are you breeding your fish? I have gotten my cichla to lay eggs with 4 water changes a week. Have you thought of adding a uv sterilizer may help with water clarity. Just curious and trying to help