A fresh water change is like a breath of fresh air after being stuck in a enclosed room full of people farting, sweating and burping after having a meal of curry, durian and whipped potatoes!
From my experience, there are so much immediate benefits that I wonder why its so unmotivational when you will see corals having a growth spurt, looking better, having microlife explode again, stopping nuisance algae in their tracks until the nutrient levels creep up again...
so get off your lazy butts, ye scurvy dogs and do that water change now!