I bought this for my 15 gallon tank because I wasn't sure that the QF10 was doing the job. This filter is WAY overpowered for my tank. It displaced all the sand and scared my Julii Corydoras into hiding. I used it for a total of 7 days - and bought it brand new. So, essentially, it's a new aquarium filter. Asking less than I paid for it. I can leave it 'unwashed' so you can have the advantage of the biofilm to seed your tank. Or I can wash out the filter and biosponge. Your choice. My tank was clean and the cory's were quarantined AND the only fish in that tank right now. I attached a copy of my Ebay receipt as proof that I didn't receive it until February 7th. To 'sweeten' the deal, I will throw in an Aqueon20 casing that I got on FB Marketplace. When I got it home, it was missing the plastic pieces to hold the filters and I could not get the pump working. You may have better mechanical skills than I do to get the pump running and at the very least, can use it for spare parts!