Media in a bag is not as effective as in a reactor because of the poor water flow inside the bag. Moving the media bag to an area with less flow would further reduces the effectiveness.
I put GFO in a media bag in my filter sock and I put carbon bag under the floss in the bubble trap before return pump. GFO in sock makes it easy to flush bag out when I change sock and same with floss, which doesn’t need changed as often. I’m using a trigger sump and it comes with a coarse sponge for the bubble trap but it was difficult to clean so now I just cut strips of floss and replace them as needed, has worked well and catches more particulates than sponge.