Eheim 2026 tubing size questions...

[glassbird]

Could someone please explain this stuff to me? I will be looking at a used Eheim 2026 tomorrow. The owner has said that he cut the original tubing in some way to custom fit it to his tank, and I will most likely need to buy replacement tubing, including the intake part and the spray bar. I have been looking around online to see how much this stuff will cost, and I am confused by the connotation of "12/16 mm". What is this? I understand that the intake side of the 2026 has tubing of 16mm, and the outgo is 12mm. Is that it? If I get a set of "12/16mm" tubing, will I get one tube at 12mm and a second tube at 16mm?

How do the installation kits work? I do not like the intake and spray bar that seem to come with the new ones. The gray version would be preferable. Do you have to get a specific size of those kits for different filters? Is there a kit number for the 2026?

Any input here would be mighty appreciated...