If you haven't you are going to want to start with the thread below. The next step is going to try your best and identify what sort of algae it is. I understand you said GHA but is it or maybe something else or another stand of it. Lastly, and I have used Vibrant with success against GHA, I would suggest to remove what you can manually( as
@AZMSGT said ). I know this is tedious but it is a great option. Put on some music, grab a cup of water to rinse your fingers in, nitrile gloves if you want, and:
1. Reach in tank safely
2. Pull GHA off the rock. Gently. Pinch a bit, twist and lift, gently
3. Lift hand out of tank, move to cup of water I noted, place GHA inside water, rinse fingers
4. Repeat for 20 or so minutes
5. Take a break
6. Repeat for another 20 minutes or so or until you are satisfied
Now you can restart Vibrant. Please note that when using Vibrant that while it works you are going to have an increase in nutrients. Meaning you have to have a good working skimmer and should toss in a bag of carbon. Over the course of about 2 to 3 weeks, maybe 4, it should clear up assuming the dose is the correct amount.
The thread has some great info in it with various notes of success, failures, and return algae. I fell into the returning algae after mine was nocked out. I saw it working within 24 hours on my tank walls. Day by day GHA disappearing from various rocks. Then one day it was all gone. However, it came back with a vengeance because I didn't manage nutrient export so had to go for round 2

. I have some images in the thread below. Good stuff, it does work, but I jump started mine by manual removal of what I could.
Hello Everyone, We had been asked to come on this forum and answer a few questions about Vibrant for a few users here in different threads. We thought it would be a good idea to start a discussion thread about Vibrant, how it was created, what is it, how it works, etc. Then there will be a...
www.reef2reef.com