Cascade canister return pipe is constantly sputtering air

[Snagrio]

I have a 125 gallon with two Cascade 1500 canister filters, and over the past couple days I have been dismantling the entire setup for a complete overhaul (replacing substrate, decor, ect.). Well yesterday I finally got everything back together after much trial and error but, now there's another problem. On the tube that puts water back into the tank, one of the filters is perpetually spitting air out along with the water as if the thing was freshly primed, but it's been running since last night and still doing this.

The thing is I messed up royally twice while setting everything back up. First, I put the input and output ends on the wrong sides so I sat there for several minutes wondering why nothing was working (i.e. the intake tub was pushing water out). And then after figuring out my mistake, instead of doing the smart thing and just switching the input/output pieces in the tank I decided to unscrew the entire tube off the canister, which led to water exploding all over the floor. Finally managed fixed and running despite all the mishaps but, that same tube I unscrewed is the one constantly spewing air along with the water it's putting back into the tank so, did something get damaged?

The other filter has been going fine from what I can tell which is why I'm suspicious that something went awry due to the "extra" tube mishap.

 

[Colin_T]

It's probably sucking in air at the connection. Make sure the hose is on the connector correctly and check it all for leaks.

 

[Snagrio]

I had figured out the issue. The pipes were tilted at an odd upwards angle and the water level was slightly lower than normal (as it was just before I was about to add a bunch of hardscape) so they kept getting air backed up into the outlet. Now I have outlets leveled and the water level's raised again so there's no further issues.