I’m getting e-liquid leaking from the tank

Try the following:

Check that you haven’t overfilled the tank causing e-liquid to pool within the central tube. Leaving a small amount of air within the tank also creates a vacuum which helps to stop vape juice leakage.

Make sure that all of the components are properly threaded, but not over tightened.
Examine the O-ring and seals within the tank to see if they need cleaning or replacing.
Check that the tank glass isn’t cracked - if it is, we stock replacement glass for a wide range of atomisers.  
Leave your vaping device standing upright when not in use.
 

If none of that worked:

Your vaping style may be more suited to a different tank; or you might be vaping a high PG liquid that is unsuited to the style of tank and coil that you’re using. Talk to us about which of our wide range of atomisers might work better for you.