Carbon and GFO - Is that why My Coral Colors have Faded?

For a While now I have been trying to figure out why my Corals have Faded in Color?



SPS, Acans, Chalices, some Favia.



It seems only Zoanthids will hold their Color for me.



I cannot get these Corals to keep their Color for some reason.



I do Weekly Water Changes and Dose Acro Power Twice a Week as recommended.



All my Parameters are Spot on too.



Temperature - 78.5

Salinity - 1.026

Alkalinity - Now 8.6 was 7.7

PH - 7.8 to 8.1

Ammonia - 0

Nitrite - 0

Nitrate - 0

Phosphate 0.08

Calcium 440

Magnesium 1460



I have come up with many Theories.



Low PH - People said that would not cause it

Low Alkalinity - I was told to raise it from 7.7 to 8.5/9 but that didn't work



Now somebody told me it was because I use Carbon and GFO.



They told me to take it out completely.



But I am very very worried about doing that as I have been doing it for a long time.



Do you guys think that that is the Problem?



Should I stop using those two things?



If you have any other ideas let me know.