I must commend the customer service and here seems a good place: offhandedly while making my order I mentioned needing a sponge filter and without hesitation they offered me a filter from their own tanks, cycled and with attachments! They were incredibly responsive, offering me some different sizes as well to fit my tank. Though the bacteria may not have survived (I’m no bacteriologist so I have no idea how this works,) I can’t recommend this seller enough for their infinite patience.