I just put together a water cooling system. I seem to always have a leak on one of the nossles coming from the threds of where the barb connects to the resivor. I tried 2 different nossles with no preval. I used the crome barbs and that leaked where it connects to the resivor. I had to lossen it with pliers. Then I used the Swiftechs barb which is plastic. And that seemed to have worked for a bit but with a couple of splaters of coolant at the bottom of the case. I'm getting tired of where it is leaking so I'm wondering if I can thread it with Nilon threads like you would use for pool pumps.
I guse it would help if I gave you the specs of the res. It's the Swiftech MCRES Micro Rev. 2 Small Form Factor.
First, inspect the res for any cracks that might have occurred due to overtightening of the barb.
If you find none , a couple of wraps of teflon tape high up on the threads of the barb will probably be enough to stop your leak.
You could also use some silicone sealant, but would have to give it some cure time before refilling the loop.
Its very likely the barbs were overtightened at some point and caused some tiny cracks around the thread fittings. The only way to fix this would be to use some epoxy or sealant which will likely also mean you can't replace those barbs going forward. Like delluser1 stated, you could try teflon tape, but not sure if it would hold as a semi-permanent solution or not...worth a shot. Also...yes, if you use any kind of sealant, give it some cure time before putting it back under water.