bought this skimmer from another reefer last week, using now for my 4ft tank, i already have a H & S 110 out sump skimmer, try to use two skimmer but not sucessful when ever my backett is on , h & S will stop skimming, may be backett is more prowerful then h & S , so i have to let go one of them. you are welcome to view the backett in operation before confirm the deal. thanks