Sub tanks explained
What is a sub ohm tank?
Sub ohm tanks (also called sub tanks, sub ohm clearomizers, or sub ohm clearo tanks) have both a generic definition and a specific marketing definition. The generic definition of a sub ohm tank is any atomizer tank where the resistance of the coil (or the aggregate resistance when multiple coils are used) is less than 1.0 ohm. The specific marketing definition is a tank of less than 1.0 ohm coil resistance that is designed to use and comes with a pre-made, factory-built, removable atomizer head containing a coil or coils with wicking material that screws into the base of the tank and can be replaced with a new head.
History of atomizer development
Sub ohm clearo tanks evolved from various stages of atomizer development. Dripping atomizers came first — a coil on a ceramic base inside a cylindrical metal shell, which screwed into the base of a mod (power source) via a threaded connector that also provided electrical contact. E-liquid was dripped into the open end of the tube directly onto the coil.
Some atomizers were marketed with two sections that fit together — one cylindrical section for the coil, and another that was stuffed with wicking material (usually silica fibers).
After that came clearomizers. These were single-piece cylindrical metal tubes, open at one end with a connector at the other, where the coil was usually installed vertically, with wicking material wrapped around the coil. E-liquid was dripped into the open end of the tube until the wicking (silica or polyester fibers, but occasionally more exotic materials such as blue foam for fish tanks) was saturated. This allowed longer vape times before refilling.
Next was clearomizer tanks (vape tanks), which used a clearomizer whose metal tube had holes punched or drilled. The clearomizer was then installed inside a sealed plastic or glass tank that held a larger quantity of e-liquid. Inhaling through the drip tip created negative pressure inside the tank that forced e-liquid into the clearomizer, saturating the wick. Early clearo tanks were homemade by cutting plastic syringes into sections.
Not long after that development, factory-built clearomizer tanks appeared. Gone were the punched metal tubes inside the tanks. These clearo tanks had fixed coil “heads” with long wicks that extended into the e-liquid reservoirs of the tanks. Stardust Tanks, also called CE4s, where the first really successful disposable tanks. That genre was followed by non-disposable tanks whose heads could be removed and replaced.
Through these years of atomizer development, the coil resistance was almost never lower than 1.25 ohms, and could be as high as 5 ohms.
Then the sub ohm craze caught fire. Vapers discovered that ultra low resistance allowed higher power vaping that provided a much more intense vaping experience — better flavor and much more vapor production.
The first sub ohm tank was the Aspire Atlantis, followed soon by the Kanger Subtank. These were glass tanks with removable/replaceable clearomizer-style coil heads that had resistance as low as 0.5 ohms. Soon after that the flood gates opened, and every ecig hardware manufacturer came out with its own sub ohm tank or, very often, complete line of tanks with custom heads — horizontal or vertical coils, organic cotton wicking, in single, dual, quad, or even eventually octet coil configurations, and at resistances down to 0.15 ohms (for nickel Ni200 temperature control coils).
2015 was arguably the Year of the sub ohm clearomizer tank. They were amazing. 2016, however, is the year of the RTA. While sub ohm clearo tanks are still very good, the crown of vaping now goes to the best of the new generation of RTAs.
Sub ohm tanks vs. RTAs
Technically, the difference between a sub ohm clearo rank and a rebuildable tank atomizer (RTA) is that a sub ohm tank uses pre-built factory coil heads, while an RTA has a deck on which the vaper installs his or her coils (either homemade by hand, or purchased) and wicks. The clear waters that distinguish an RTA from the sub ohm Tank get muddied, however, by manufacturers offering RBA deck heads for their sub ohm clearo tanks. This gives buyers the choice of using disposable sub ohm factory heads or building their own.
RTAs have generally come with more spacious, higher-quality build decks, but even that is changing. Some recent clearo tanks now come with very good Velocity-style build decks. RTAs have continue to move forward in development, however, with features such as e-liquid flow control, which most sub ohm clearo tanks don’t have.
Tips and tricks for getting the most out of your sub ohm tank
Prime the coil head before first use
Before using a new coil head for the first time, it should be “primed.” E-liquid should be applied to the head’s inlet holes or slots to wet the wicking just inside the shell, then 2-4 drops of e-liquid should be dripped into the open top of the head, directly onto the coils and wicks. Let the head sit for about ten minutes before initial firing to allow complete absorption into the wick. This prevents burning the cotton wick because it’s dry.
Break in the coil head gradually
With a new coil head, start firing at low wattage, say 20 watts. You won’t get much flavor and perhaps no vapor at all, but that’s OK. You’re letting the coil head ease into doing what it does so well, and this is essential. Then gradually increase the power in steps over a period of minutes or even hours. No matter how well-primed a new coil head may be, hitting it with 70 watts of power right off the bat will probably shorten its life span dramatically.
Keep tissues or paper towels handy
Vaping is messy. There’s no way to avoid spilled or leaked eliquid. Whether the discussion is about RDAs, RTAs, or Sub Ohm Tanks, keep a box of tissues or a roll of paper towels within arm’s length. You will need them to wipe up e-liquid spills or clean up leaks.
Replace the coil head when necessary
Coil heads that last forever are the holy grail of vaping tanks, and manufacturers are moving in that direction with ceramic heads and plate technologies that eliminate coils completely. They’re not yet there, however.
Coil heads wear out in two ways: 1. the coils themselves gunk up with residue and burned carbon, and 2. the wicking material gets burned or fouled and either loses its ability to wick e-liquid to the coils.
The easy way to tell if your coil head is dead is to vape. If the flavor diminishes or gets funky, it’s time to change the head. Sometimes, however, we’ve forgotten how great the coil head was when new, so we don’t notice reduced or tainted flavor. For that reason, a second, visual method is needed:
Whenever you’re about to refill a sub ohm tank, examine your coil head. Look down the open top end. Is the wicking material still white or darkened toward brown or black? If it’s black, it’s done and needs to be replaced.
Rebuild coil heads if you wish and can
For vapers who have the parts and skill and who enjoy rebuilding, many sub ohm clearo heads can be rebuilt with surprising ease. That’s not as quick as unscrewing an old, worn out head and screwing in a new one, but it can be both satisfying and inexpensive for those who enjoy it. Rebuilding factory heads gives the vaper control over wire type, coil build, wicking material, and resistance.
If that appeals to you, hundreds of videos on rebuilding factory heads are available on YouTube. The learning curve isn’t essentially any more difficult than learning coil builds and wicking for an RTA.
If it’s not your thing, however, don’t sweat it. Just buy another pack of replacement heads, and you’re good to go for six more months.
What type of vaper are sub ohm tanks best suited for?
Sub ohm tanks are ideal for vapers who want a more intense vaping experience, usually at higher power, and with ease and convenience — prime a coil head, install it into the base, fill the tank, gradually ramp up, then vape for days. Vapers who love sub ohm clearo tank typically don’t want to drip (as RDAs require) or build their own coils (as RTAs require).