When I used it - I left the cup off the skimmer for 2 days - did the water change added back the carbon. Then I opened the outlet of my skimmer so that the max water was going back into the sump (ie. lowered the level of the water/bubbles in the skimmer). Then took a silicone hose from the skimmer cup drain and led it to a 5 gallon bucket - and treated it like a water change. took about a day of wet skimming to get it back to normal. (I put SW in my ATO) instead of RODI during that time - I think I had to empty the bucket one time.