I bet the carbon and phosphates removal media will take care of it. You probably stirred up a bunch of crap when you moved the contents of your fuge. Looking at the pics, it doesn't look like you have any macro algae? Just a mangrove tree? I'm not saying that that isn't enough or it's bad, because I don't know...
I'm always looking for better ideas to improve my system. I've been struggling with keeping nitrates down to 20, and I'm doing a 40g WC every day to keep it at 20. I figure it's the move from the 120 into the 450 just has crap stirred up so I'm going to continue with the WC's for a while.