I have a 125g freshwater fish tank with 5 goldfish in it and two emperor 400 filters in it. The water has always been clear since I've owned it for the last 4 months until I added my second emperor 400 filter and then the water turned from cloudy to green within a week so someone at my pet store told me to do 50% water changes every 2-3 days until it clears up then do my regular 25% water changes a week. but this has been going on for two weeks and I don't know what to do please help!