I have a question...does the foam filter pads, specifically the fluval U and Plus series have special characteristics? Or like many people say...do they get the foam from the same place as everyone else and just put their own name on it and charge double the price? The reason been, I've found some foam pads on ebay that are 18" x 12" for Ã‚Â£5 which would last me for a rather long time...and is only a fraction of the price of a pack of official fluval foam pads. Will they do the job just as well? Any opinions?