I will be possibly purchasing an eheim external filter in January and ive never had an external before and i was just wondering do they give much surface aggitation?
it all depends on the return.
If you use a spray bar then yes it will agitate the water. I keep my spray bar below the water level due to the noise of the spray effect.
I have a 2026, and it does come packaged with a spray bar.
Even if you are buying from a internet company, you should get it as it comes in the box.
If you are buying 2nd hand, then obviously you would have to check.