Zoa colors fading from carbon dosing

[Animal-Chin]

So my nitrates hit 20, algae started showing up so I thought I'd carbon dose. I use NOPOX from red sea and have been doing so for over 2 months. Good new, my nitrate fell to 5, bad news, my zoa's all faded in color.

Anyone know why this would be? Have suggestions to color them back up? Nothing else in my tank has changed other than the carbon dosing and the fading started right after I started the dosing.

Are my nitrates and phosphates just too low now? Do zoa's react to the carbon?

I know some will say "stop carbon dosing" but my sps are lovin it and my algae is totally gone so I'm liking the dosing as I feed heavily and have big fish.

Thoughts?