Eheim 2215 installation ...Im confused!

Yup, you're supposed to cut it in half, and then cut two more parts 2-3 inches long, one part from each half.

Here are pics of my setup so you know how to set up the valves:

thats one way of doing it!

Both of the curved pieces are for the output. The tube holder is to help the tube curve into the tank.

Nice pics SanguineApple - I see you even plumbed the valves in opposite directions - a nifty touch I was going to suggest.

More info -

Quarterly maint. drill:

Unplug the filter,
close all 4 valves,
while holding a dish towel, unscrew the couplings (you'll have about a tablespoon of water to catch from each of them).
Transport the entire filter to a countertop next to a sink, have a bucket of treated water, or fairly clean aquarium water handy.
Open the outlet valve and pop the snaps so you can lift the pump assembly off the canister.
Gently turn the bottom inlet tube downward so you can drain the filter's contents into the sink. While draining, jostle the canister a bit and keep adding the treated water - you should see a fair amount of crud going down the sink.
Carefully reattach the pump to the canister (don't nick the O-ring), close both valves and reattach the lines from the fish tank. Open the outlet valve, then the inlet valve and, after the canister has refilled, plug the pump in again.
It will make noise for a bit, then quiet down. A little tipping in various directions may hasten the air purging process.

You should notice improved flow after doing this. Do this whenever you notice a decrease in flow. For a new one, probably 6 months, then every 3 months after that. If your improvement is marginal, you can go a step further by removing each layer of media in turn and rinsing them (in treated water) in an ice-cream bucket. Assuming you have the Eheim media (rings, pad, cocoa-puffs) - if your stack gets slack, toss a couple of all nylon pot scrubbers in the bottom to firm things up.

One more thing - It is not a bad idea to drill a ~1/8" hole in the U shaped tube on the long arm a bit below the water line (a bit below wherever you're willing to let it evaporate to before topping off). What this does is break the siphon to the pump when the tank water gets too low.

Why do this? Think about why your tank water would get too low... Either you're in the middle of a water change (use a little gob of poster putty to plug the hole when you're doing this) or your canister has sprung a leak. The later usually happens right after you've left for several hours. Regardless of the myriad reasons behind such events and the relative rarity of them, that little hole may well prevent the contents of the tank down to the basket from draining out.

Another task - regularly inspect the hose/plastic barb connections. Unscrew the lock nuts and make sure the hose has been staying where it ought to be.

Awesome directions, Squawkbert, and excellent call on the suggestion to drill a hole in the U-shaped tube. That's a lesson I learned too late, after joining this forum. I had half of my tank drain out through a crack in one of the double tap connector valves a day after I set up the tank. Had I drilled that hole beforehand it would have saved me a whole lot of cleanup and anxiety. Luckily, I had no fish in the tank at the time.

I feel like a real dumbass asking this after you all already explained how to set this up... but, I have done everything the guys in the store said and the filter is making a knocking sound. The manual says this will stop, but it has been doing this for 1 1/2 hours. Is this normal? What am I doing wrong. Any advice you have would be greatly appreciated as I changed from the Emperor 400 to the Eheim and have no idea what to do with external canisters.

Thanks!