Cheers for the link, but I see that's 10/16 tubing. 10/16 or 12/15 might be options, but ideally I'd like to use something the same dimensions as the Eheim hose. I can find 12/16 from a couple of places, but getting it in anything less than a 30m reel has proved to be a challenge.
Looking at the forums, it seems a lot of people are looking to replace Eheim's ugly green hose. So I guess if did get a 30m reel I'd have little trouble selling the excess in shorter lengths on Ebay...
The simple solution is of course just to use a 12mm hose-to-hose connector and hook a few inches of green Eheim hose to my filter, then connect some clear 12/15 hose to that and run it to the tank. That's probably what I'll end up doing, but with the potential for leaks in mind I'd rather keep the number of connections to a minimum.