I don't thing this will make anyone mad, but since you have a Bak Pak 2 as I have. I will post the site so you can get all the info you would like, it was a huge help to me at first.
www.cprusa.com go to there message boards for any info on their products. Also caution, on the outlet tube that goes back to your tank that the sponge goes in. It can overflow the water in the bak pak if it gets clogged up. And if you have any good size snails they can block the tube as well, you will need a mod of some sort from the tank side to keep large snails from entering. The sponge works well for micro bubbles but after weeks of messing around and breaking in the Bak Pak you will not need it. The venturi should be open all the way for best results, Open all the way it creates slow water to reduce the micro bubble to zero and extends contact time with your cup. I have learned about my skimmer in and out and don't use any sponge or even bio bale. I use the back of it for other things; However, cpr does not recommend that you do that and if you are not careful to what you put back there you can clog it once again, so I won't mention anything until I take pictures of everything on mine and what I do to make it safe, sorry. The Mod for the outlet tube I used is a little complicated to actually explain but think of something like two Ty wraps going across the outlet tube or even two elastic bands so large snails can't enter but water can still exit regardless of particles that may go from the skimmer to the tank. Last Hint once you get used to your skimmer and learn tricks like keeping the venturi open and pump off the tanks glass to quiet it down look into buying the Preskimmer box it does wonders for tank surface water and keeping it super clear, but this piece also takes some time to get used to as you will find out the water level needs to be close to perfect in order for the overflow effect to take place. If you get it some day post it and I should have pics of everything by then to show you how I maximize all my cpr products. Good Luck