nyyanks,
are you saying that 1/2" tubing will still work fine even though the holes are 3/8" and 1/2"? When i say holes, i'm referring to the images i took above w/ the ruler.
richyoung,
Thanks for all the measuring

. My main concern is if my 1/2" tubing will work as-is or if i need to purchase any additional attachments to make it work with the Eheim 1250.