I will use a 20L I have laying around to practice. Keep in mind that this will be a fuge only. I have a 55 that will be the actual sump (skimmer will be there), so there will be lots of opportunities to weed out the bubbles. I just need to get a basic design going for the fuge as I need it up and running pretty soon (by Feb 14th). You have given me some very good ideas for this. If you have anything else that you would add, please let me know and I will look into it. Thanks for all of the time you took on this Vinh.