The Dragon's Rose's post in WC= flourescent algae?!? was marked as the answer
Figured it out! I add ciclid salt (VERY small amount) because water from my tap is crazy soft. I've been tossing it around the tank lately instead of just dumping it in the water, and apparently it's killing the algae, which causes this odd orange color. It's actually pretty cool to watch now that I know what's causing it!
Just thought I'd update in case someone else ever has this happen!