do you have corals? do you have a sump if yes do you have Chaeto in it? I would stop using chemipure and just run the carbon, you can even pit it in a media bag and put it in your sump if you have a sump to clean up your water. GFO is mostly used if you have phosphates, used to reduce phosphates.
If you wanted to use both you can. you can connect it with a pump or connect it to a manifold. Just do a quick search on youtube on the reactors so you get an idea how to hook it up
for example I am starting a new tanks and I will use carbon in one media bag and phosphate minus from Aquaforest to reduce the phosphates that will leach out of the dry rocks.
after a month or so I will remove them and use as needed. if I see water dirty or anything I will put a bag of carbon in the sump.