Not all of it. From my reading the Gel that you are refferring to is massive colonies of bacteria. Some of it will end up in the display tank and get eating by fish or corals which is the beneficial part but with all things in your tank there is a balance. Too much can throw off your bacterial population. Most articles I read have expressed that you should have the output of you reactor near if not tied into your skimmer intake. You want to keep the bacteria under control and having it tied to a skimmer allows excess parts of the gel to be removed.