what kind if T-junction would I need...

[reybie]

to make use of this freshwater surface skimmer with an eheim 2217. It would be even better if I can the T connector from a local hardware shop

 

[is300zx]

You don't really need one of those if you aim your spray bar so that that the water agitates the surface.

 

[reybie]

I have filmy stuff on my water surface. I've been able to get rid of it with a HOB but it came back after a few days. I'm trying to avoid using another hanging filter.

 

[is300zx]

Surface agitation usually takes care of the film so just aim your spray bar upwards so it's agitating the surface of the water. IMO those surface skimmer are waste of money.

 

[Wonko The Sane]

I've used one of those skimmers, and it worked just fine with my canister filter. I didn't need any kind of T-Connector. The skimmer draws from the top and bottom simultaneously.

The skimmer you linked to works better than the old-style eheim skimmer which had the hinged skimmer funnels, and it's quieter, and much cheaper as well.