My boyfriend and I started out 37gal reef tank with a 5 gal sump and a large refil a filter about 5 months ago. We have a lawnmower blenny, mandarin fish, 7 turbos, 3 asteca snails, banded shrimp, cleaner shrimp, a few sand sifting snails, a pair of maine blizzard clowns, a green bubble tip, and about five small frags of soft corals. Everyone is happy and healthy, but the water gets DISGUSTING VERY QUICKLY. We have been doing about 2-3 30-50% water changes a week for about 3 weeks, just so we can be able to see the back of the tank. The water is green and has a bunch of copepods. Does anyone have any suggestions on how to clear the water while still keeping some copepods for the mandarin fish?