Brs carbon gfo reactor

[Bruce7267ad]

So I got this reactor for pretty good price new and I'm not sure if I should even be using carbon or a gfo in my tank how do you know if you should be using these things?
Thanks guys.

 

[35ppt]

Only use GFO if you need to lower your Po4 (0.08 is a good target). Carbon I have run both constantly and intermittently.