You can buy GFO in bulk and get a media reactor is probably the best method to implement GFO.
Looks like my previous experience with various forms of algae in the display. I've dealt with turf, briopsis, dino, brown, cyano, hair, etc at various stages in the past caused because of one reason or another. Like starting with dry rock that was chock full of phosphates, upgrading to a bigger tank and using more dry rock that was chock full of phosphates, tank accidents causing mass die offs and recycling of the tank again, etc. Been a fun roller coaster ride...
The most important thing to do is have lots and lots of patience. No matter what you do it will not go away overnight. Well, except a complete tank break down but that is rather drastic and unnecessary IMO.
But there are a lot of ways to go about this. What's worked the best for me in every instance was to:
1. use GFO in a reactor to get the phosphates down below .1 to around ..03-.06.
2. Take a few minutes a night as time permits and manually pull some of the algae out as that will export the nutrients it has absorbed and not release back into the tank as it dies.
3. Maintain a consistent water change schedule. Like 10% weekly for a while. I'm currently doing 1% daily.
4. Then use some form of carbon dosing to help maintain lower nutrients. I started with a form of biopellets and then moved to vinegar dosing and still do that on a daily basis.
5. Keep my skimmer clean
Doing those steps and keeping consistent with each one did it every time. Every time I can see when the algae is dieing off and once that happens I usually get a short outbreak of cyano before that blows off too. It takes several months but it's worth it to not freak out and do anything drastic.
This past mishap due to some cleaning supplies and a mass die off has taken 4 months starting with GHA, and turning to brown sludge algae, and then the cyano, and now my rocks are basically cleared off now except for a bit of dino here and there but it's going away as well. That's probably the hardiest of everything I've had. Bryopsis after that but I didn't get that this time around.
But no mater what you do, have patience. Good luck.
