Stockman Standpipe tuning?

[thedraque]

I am setting up a 90g tank with a single drain ive never setup a single drain before i built a Stockman and am using a Jebao 4000 return pump with roughly 6 ft of head. with the pump on full blast the water is just at the very bottom holes drilled in the stockman and it is making a loud gurgling noise, tuning the air valve on the top has no effect whatsoever, does this mean I just need a stronger pump?

 

[Saltyreef]

You can try a long airline inserted into the hole of the cap down into the pipe.
Different lengths have rendered different results.

Im also a fan of the lifereef silencer. It made my single drain dead quiet.