How can I increase low-copy plasmid DNA yields using QIAfilter Plasmid Kits?
FAQ ID -1062

If low-copy plasmids are used with QIAfilter Plasmid Kits, the cell lysates of two QIAfilter Cartridges can be filtered into one previously equilibrated QIAGEN-tip, resulting in doubled DNA yields.

Similarly, if low copy plasmids are used with HiSpeed Plasmid Kits, the lysates of two QIAfilter Cartridges can be filtered into one equilibrated HiSpeed Tip.