3 days later and the tank is starting to stabilize again.
Now that it's crystal clear, the light seems much brighter and the moss has fresh green tips. I'm going to say it's from the time it spent in my big tank just to be rational about it...but I can hope too. I don't want to dismantle the filter and light because that's what I spent $60 for...but then again if I have to then I'll at least come out of the deal with my first rimless open-top tank.
I can't wait for the parameters to settle and get shrimp in