Thor, or should that be Zeus?

[Chaz]

should be fine I'm using standard fish tank pump with a 13mm reducer the main thing is the head height and you have 2.5m which should be more than enough.

The chiller does it have it's own pump?

Ye, and its much too powerful. I made an adaptor to go from 12mm to 5mm and it blew it off immediately. The chiller is more powerful than most coolant pumps ive seen at full whack :-) Theres an idea ...