Simply Koi and More Koi

Hi I'm after something along the lines of a oase screenex 36 or the screenmatic, I'd even consider the biotec 30 or a roto concept.

Basically I'm open to any suggestions but must be pump fed, I've got 8000 gallons but I've already got a multi bay but need more filtration, please let me know what you've got or suggest something!

Thanks in advance

Stuart