hi, total newbie here at petforums. we have a marine tank that has been established for almost three months. we have lots of live rock, one coral, four percula clownfish, three emerald crabs and four snails. I feed them dried shrimp brine twice a day. I have two power jets and a tetra whisper filter. here's my current stats:

temp: 78
ammonia: .25ppm
nitrites: .5ppm
nitrates: 20ppm
ph: 8.0

water has been cloudy (milky) since 10% water change and gravel vacuum performed about five days ago. everything seems to be surviving and doing fine, but I don't like the milky water or levels. any ideas? please help! another water change? larger one?