This is a sign that liquid has entered the central tube. This often happens after refilling.

To solve the problem, clean the central tube of liquid. To do this, disconnect the clearomizer from the battery without emptying the tank, wrap its bottom in a towel or cloth and blow through the mouthpiece.

If bubbling persists after filling:

• The problem may be caused by a faulty or worn-out atomizer. Replacing it should solve the problem.
• The problem may also be caused by the way it is used. Unlike traditional cigarettes, inhales with an e-cigarette should be softer and longer, allowing the liquid to fully evaporate. A strong and fast inhalation can cause unevaporated liquid to enter the tube and cause bubbling and leaking.
• If possible, keep the tank full and never let the liquid level drop below 1/3, or below the "windows" with cotton in the atomizer. This helps maintain a vacuum in the tank and prevent leaks.
• When removing the base to fill your atomizer, make sure the seals are intact and prevent loss of hermeticity.
• Seals provide a good seal, so make sure you don't overtighten different parts.
• Make sure your atomizer is installed correctly, otherwise it may lead to poor contact and inadequate power transmission.
• Avoid liquids with unsuitable VG/PG for your tank. Too liquid liquid will saturate faster than you need and there is a high risk of leaks.