If you haven't started injecting co2 into the reactor, there shouldn't be any gurgling. Hopefully you filled up the reactor to the brim with tank water before closing the top. If you didn't and there is a small air bubble, don't worry about it. It will be dissolved into the water within a few hours (same concept as with co2).
Since you have it hooked up to an eheim 2217, do you have the input and output on the reactor the same size or different? Do you have a clear reactor so you can see what's going on inside?
A few things that I wish I did when I first built my reactor that I had to learn through trial and error....
- use vaseline to seal the top threads
- stick the co2 tube about 1/2 into the reactor
- get a cheap pot scrubby and put it at the bottom, not the green brillo pad...a pot scrubby that looks like a pom pom
- you don't need a retarded high working psi, this isn't a diffuser. 5-10 working psi is more than enough. turning the psi higher just seems to create a bigger bubble at the top.
- its okay to have a small air pocket at the top as long as you can 100% make sure it is only co2 in the air pocket. this is why I began using vaseline to seal the top threads after reading the DIY cerges thread.
- there shouldn't be an air pocket in the AM. co2 dissolves fairly quickly. if there is an air pocket in the AM, something is wrong. your filter is either spitting out bubbles or your reactor is leaking somewhere.
- if you run a surface skimmer attached to your intake, be sure that it is not sucking air into your filter. any air sucked into your filter will be spit into the reactor reducing its effectiveness.
- you want enough flow going into the reactor that it churns the water really good, but not too much flow that it is blowing bubbles down the bottom and out the tube.
- if the reactor has a huge bubble build up in a short amount of time, you probably don't have enough flow running through the filter. if the reactor is spitting out lots of bubbles and you don't have a big bubble at the top, you probably have too much flow running through the filter. on my reactor, I get a small 1" bubble build up at the top near the end of the day. within 1-2 hours after lights out the bubble is gone.
- if you have a ph controller or can afford to get one, it works really well with the reactor. i know alot of people on this forum don't like ph controllers, but I love mine. it gives me peace of mind that I have a safety net.