It is hard to tell in the photo, but it looks like the leak is coming from the bulkhead to pvc pipe connection. You may be able to solvent weld it in place and get it to seal.
This is not ideal but this is where we are at.
To do this you should first drain the line so there is no water pressure in the pipe. If you can add a stand pipe on the otherside of the bulkhead to keep the water out then you will not need to drain the tank while at the same time be able to drain the line completely.
Dry the pipe. Apply primer to the entire connection. Apply PVC solvent to the connection (preferably a thicker version), don't over do it.
Allow that to set and try try again.
Again, this is not ideal but it will work if done correctly and will hold up over time.
This issue comes up a lot due to most hobby grade bulkheads being made out of ABS plastic and not PVC. The dissimilar plastics do not bond well with standard PVC solvents.
There are bulkheads that are made out of PVC as opposed to the cheaper and more brittle ABS. The ones made by Lifeguard Aquatics are made of quality PVC and remove this issue entirely.
Another solution is to use a PVC to ABS solvent that is made just for this type of application.
Spears ABS to PVC-94 plastic pipe cement