Can you provide a link to what this is? Did you follow directions, some meds turn water colors while treating them. What are your water stats, ammonia, nitrate, nitrites?
I checked and found confirmation that that med has malachite green in it, so that's what tuned the water green. It should stay green over the course of treatment. When you're finished using that med, you can put some fresh carbon in your filter to remove what's left of the med. along with the partial water change that it probably recommends.
