What Just Happened???!

Ok Ok Ok, so I have posted earlier a thread about my Alk being 11.5. It still is last I check. I did a 2 gallon water change today for my weekly maintenance. I noticed though yesterday that my water went from crystal clear to slightly cloudy. I have complained about my duncan being shriveled 99% of the time. At night he seems to open up, HE'S HUGE! Well I just got home from work and my tank looks like I just added sand to it. The water is super murky. Tank has had livestock in it for about 3 weeks now I believe. Whats going on here? pH=7.8

Ammonia=0

Nitrite=0

Nitrate=0



Oh and I am using carbon filter media, filter sock and the standard protein skimmer... feeding frozen brine