# Sub-ohm tank: power, draw and what it suits > A sub-ohm tank changes everything: dense vapour, an airy DTL draw, high wattage. The lab sets out when it suits a British setup and when it does not. Thick clouds, a draw as wide as a breath, flavour that fills the mouth: the picture is familiar to anyone who has stood near a cloud chaser. Behind that signature sits one specific piece of hardware, the **sub-ohm tank**, routinely presented as the natural next step for an experienced vaper. It is nothing of the sort. It is a particular way of vaping, with its own liquid, its own draw and its own daily chores, and it does not suit every setup or every person who tries it. ## What a sub-ohm tank actually is A **sub-ohm tank** is an atomiser built to take coils with a resistance below 1.0 ohm. The prefix means exactly what it says: below the one ohm mark, and nothing more mysterious than that. That single electrical figure sets off a chain of consequences. A lower resistance passes more current, the coil heats harder and faster, it asks for more wattage from the device, and it turns a great deal of liquid into vapour in a very short puff. You can recognise the format on sight. Wide airflow slots at the base, a chunky chimney, a large bore mouthpiece and a coil head that looks oversized next to an MTL one. The whole object is drawn around volume of air rather than restriction, and our [guide to how vape coils work](/uk/vape-coils-explained-guide/) covers what sits inside that head. ## Sub-ohm vaping and the DTL draw Sub-ohm vaping only makes sense alongside the gesture it demands. The low resistance and the inhale style are one package, and separating them produces an unpleasant vape. The airflow on these atomisers is deliberately open. It lets a large volume of cool air through, which drops the temperature of the vapour and makes a direct to lung inhale possible, taken in one movement straight into the chest rather than held in the mouth first. British listings usually sort this into two bands. Full DTL means the airflow wide open and the airiest draw the hardware can give. RDL, restricted direct lung, sits between MTL and full DTL: still a lung inhale, but with the airflow partly closed for a draw with some resistance to it. RDL is where a large share of British sub-ohm hardware now lives, and it is worth trying before assuming that maximum airflow is the goal. Plenty of vapers find the middle setting gives them better flavour definition than the wide open one. ## Matching wattage to a sub-ohm tank An underfed sub-ohm coil gives you nothing. The vapour comes out lukewarm, the flavour reads flat, and the natural reaction is to blame the liquid when the setting is at fault. These coils need sustained power before they express anything at all. The reference point is printed on the coil itself. Every sub-ohm head carries a wattage range on its body or its packaging, and that range, not a figure picked up in a forum thread, is what your device should be set within. Start at the bottom of it and work upwards a couple of watts at a time. The same logic applies to the cell. A sub-ohm setup asks a lot of a battery, and the only authority on what a given cell will deliver is the datasheet published by the company that made it. Read that document, follow the device manufacturer's own instructions, and do not take a discharge figure from anywhere else. Our [vape wattage chart by ohm](/uk/vape-wattage-chart-by-ohm/) puts each common resistance value in context. ## The e-liquid a sub-ohm tank needs Liquid choice matters as much as hardware choice here. A poor match between juice and coil ruins the experience and shortens the life of the head at the same time. Sub-ohm coils want a high VG e-liquid, heavy on vegetable glycerine, which is the ingredient responsible for the volume and the density of the vapour. Thin, PG heavy liquids struggle to keep up with the wicking demand of a large coil and tend to seep out through the airflow. Nicotine strength moves the other way. Because a sub-ohm puff carries far more vapour, each one delivers more nicotine than the same puff on a tight MTL setup, which is why British shortfill ranges aimed at sub-ohm vaping are typically sold at 3 mg or 6 mg per millilitre. Nicotine salts, engineered for low power pod hardware, are the wrong pairing entirely. ## The 2 ml cap and what it means in the UK Here is the constraint that changes the calculation on this side of the Channel. Under the Tobacco and Related Products Regulations 2016, every tank and pod sold legally in the United Kingdom holds a maximum of 2 ml, and nicotine containing e-liquid is capped at 20 mg/ml. That ceiling bites hardest on a sub-ohm setup. A coil turning liquid into vapour at that rate empties 2 ml quickly, so British sub-ohm vapers refill constantly, carry a bottle with them, and get very used to topping up before the wick runs dry. It has a second effect that is easy to miss. More refills means more heat cycles and more time near the bottom of the tank, which is exactly the pattern that ages a coil head. It is also why British guidance commonly puts sub-ohm coil life at one to two weeks rather than the longer figures quoted for tighter setups. ## Coil life and upkeep on a sub-ohm setup A sub-ohm coil works hard, and it pays for that in longevity. Knowing the rhythm in advance saves you from thinking the tank has failed when the head has simply reached the end of its run. Because it runs hot and vaporises a lot, a sub-ohm head saturates its cotton faster than an MTL coil and picks up residue faster too, particularly with heavily sweetened liquids that leave deposits on the wire. Priming each new coil properly, letting it soak before the first puff, and staying inside the printed wattage range all slow that process down. The signs of a spent head are consistent: a burnt edge to the flavour, weaker vapour at the same setting, and a sudden appetite for liquid. We work through them in detail in our piece on [how long a vape coil lasts](/uk/how-long-does-a-vape-coil-last/). ## Who sub-ohm vaping actually suits Calling sub-ohm an upgrade would be misleading. It is a use case, not a rank, and the lab takes a clear position on that. It suits the vaper who wants vapour volume, an airy draw and a generous aromatic delivery, and who accepts the trade: faster liquid consumption, shorter battery runtime and a tank that needs refilling several times a day under the 2 ml rule. It does not suit the vaper who wants discretion, a tight draw or a device that lives quietly in a pocket. For that profile a restricted MTL atomiser stays the better tool, no matter how many years they have been vaping. ## Frequently asked questions ### Do I need to be an experienced vaper to move to sub-ohm? Experience mainly helps with managing the battery and choosing liquid, but sub-ohm is a matter of preference rather than skill level. A newer vaper who wants vapour volume can start there with suitable hardware and the printed wattage range respected. ### Can I use nicotine salts in a sub-ohm tank? Nicotine salts are formulated for small, low power MTL hardware. Running them in a sub-ohm tank would deliver far more nicotine per puff than intended. Keep salts for MTL pods and use standard freebase shortfills at 3 mg or 6 mg for sub-ohm. ### Why is my sub-ohm tank leaking through the airflow? Usually a liquid too thin for the coil geometry, an overfilled tank, or a seal that has not seated properly. A higher VG juice, filling without forcing, and a coil screwed in squarely resolve most cases. ### Does sub-ohm always mean more flavour? It means more vapour, which often amplifies the aromatic impression but not always flatteringly. Some liquids gain body at high power, others lose definition. Flavour depends on the match between juice, coil and setting rather than on cloud size alone. ### Can I get an MTL draw from a sub-ohm tank? Not really. The airflow is cut for direct lung volume, so even fully closed it stays more open than a genuine MTL atomiser. If you want a properly tight draw, use hardware designed for it. ## Choosing a sub-ohm tank with your eyes open A **sub-ohm tank** is neither better nor worse than a tight MTL atomiser. It answers a specific brief, vapour volume and an airy lung inhale, and it charges for that in liquid consumed, battery drained and coils replaced. Get the three variables lined up, a coil run inside its printed range, a high VG liquid at a sensible strength, and a device the manufacturer built to drive it, and the result is coherent and genuinely enjoyable. Get one wrong and the whole thing feels broken. That coherence is what we measure on every **sub-ohm tank** that goes onto the bench, and under the 2 ml British cap it matters more here than almost anywhere else, because you will be handling the thing all day long. Editorial content for adult readers only. Not intended for anyone under 18 in the United Kingdom. Vaping products generally contain nicotine, a substance that causes addiction. This article is not a buying recommendation.