I have had this CLASSIC 2000 HANG-ON-THE-BACK PROTEIN SKIMMER sitting in the garage after I took it off my 55gallon reef when I upgraded. I just checked the receipt and it was purchased in december of 2014 and used to december of 2017. Im not really sure of the value so if you are interested PM me with an offer . I have not cleaned it but if I get interest I will clean it up and make sure it operates properly. Here are some photos I just took.