Make sure your RBA is tightened down properly and check that all of your O Rings are intact. My subtank minis leak just a slight bit from the air flow using the Stock OCC
coils, but not enough that it is worrisome. You didn't state what ohm
coils you are building or your wicking material. Too much or too little wick can make it leak more, or running too low of a wattage for your build. Give more info and repost in the New Members forum and you may get more answers