Gurgling noise

I've seen a lot of advice on gurgling noises coming from the collection boxes and output to sump. All the examples are for drainage going downwards, I picked up a 75 gallon with to two drill bulkheads that exit out the side of the tank.
The first bulk head is draining properly, the second bulk head is making all the noise. Both bulk heads are connected across the back of the tank, one "L" from the second bulk head connecting to the "T" on the first bulk head exiting down to the sump.
Any ideas on how to stop the gurgling to this configuration.
Any help is extremely welcome as I've tried everything I can think of.
regards,
bh

 

One side is getting to much flow and that is what's causing the gurgle. Put a valve on the plumbing to that side so you can equalize the drainage between the two.

 

Thank you for the quick reply, however, where would I put a valve? Infront of the first bulkhead to reduce flow with the "T" joint.

There is not much room.

bh

 

As mentioned, equalizing the flow between the two standpipes might help.

Are you using low-noise standpipes (Durso, Stockman, etc)? If so, are they properly vented/tuned?