Water clarity
 

So for the last two years I've only run carbon in a bag in sump. I decided to buy another reactor and run it through there instead as I don't think passively does squat. (Had yellow tinge to water)

A day or two after plumbing in carbon reactor my water became so clear that acros were starting to bleach a little.
I turned light from 70% to 50% and slowed down reactor

Can the water become that much more clear that par increases to the point of bleeching?

Yup, absolutely!

Thought so

I also removed half the carbon

Thanks brad

I had that happen to me as well, I had to ramp up the amount of carbon so the corals weren't to shocked.

Carbon can definitely do that. For this reason I try to keep up with my carbon maintenance. If I let it slide (ie, miss a change schedule), my corals definitely get shocked when I do get around to replacing it. If I replace it sooner (on schedule) there's definitely less shock. I do love how carbon scrubs the water clean like that. Because I can see right through my tank to the other room it is very noticeable when my carbon is running out. The water goes from crystal clear to a bit blurry/murky/discoloured. Also, my carbon reactor (TLF150) crapped out once and I had to run it passively for a while. It didn't quite do as good a job as the reactor.

Carbonate type
 

Depending on brand and type of carbon used will also play a factor when running it in a reactor. Some brands actually suggest to run passive, as apposed to a reactor.
HTH

It's BRS lignite

I was using fluval passively ANSI was always under the impression that probiotic tanks should be passive.
I picked up a mr1 shorty and ties it into my mr1 that's full of hydyroton.
Within hours there's a noticeable difference