Tunze Osmolator Tubing Size?

[encrustingacro]

I accidentally cut the tubing of my Tunze Osmolator too short and need to get new tubing. I tried 5mm cobalt aquatics tubing which was too small and 1/4” tubing from a store and that was too big. What size tubing do I need for the Tunze Osmolator pump?

 

[encrustingacro]

bump

 

[KStatefan]

On one of mine I use a 3/8 to 1/4 pushlock union then 1/4 ro tubing.

 

[WVNed]

5000.390
PVC-Schlauch, ø4 x 7mm x 3m
PVC hose - diam. 4 x 7mm x 3m (diam. .15 x .27 x 118.1 in.)
Tuyau PVC, ø4 x 7mm x 3m

http://www.tunze.com/fileadmin/gebrauchsanleitungen/x3155.8888.pdf
page 57