Don't you still have the hose? According to the specs the outside diameter is 18/15/12mm, so I guess it depends on which barb adapter you're using (I couldn't even hazard a guess).
I bought a second hand pump but it didn’t come with the hose unfortunately. Think I’ll pop into my LFS as they tend to have spare parts and bits knocking around. Thank you for your help on this blaxsun., I’ll check online also.