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Submerge to detect Camo, pop Bloons and reduce ability cooldowns of nearby water-based Monkeys by 15%.
~ Upgrade description in BTD6.

Bloontonium Reactor (also called Reactor or Reactor Sub) is the fourth upgrade of Path 1 for the Monkey Sub in BTD6. The Bloontonium Reactor gains a radioactive attack with 52 range that deals 1 damage every 0.3 seconds to up to 50 bloons while submerged (51 with Naval Upgrades Monkey Knowledge). The reactor sub also enhances the prior upgrade, Submerge and Support, now removing the Camo property from Bloons every 0.3 seconds. As a bonus, the Bloontonium Reactor reduces all water tower ability cooldowns (First Strike Capability, Monkey Pirates, Pirate Lord, and water-placed Pat Fusty and Admiral Brickell's abilities) by 15% if they are within its radius. While unsubmerged, none of these attacks or bonuses are in effect, and the Monkey Sub will shoot moderately seeking darts that deal 1 damage and have 2 pierce every 0.75 seconds.

Crosspathing is generally advantageous as the default Bloontonium Reactor can remove Camo from all Bloon types, but cannot damage Lead Bloons. Barbed Darts adds 20 pierce to the radiation attack, while Heat-Tipped Darts brings the pierce up to 100 and allows the Reactor to damage Leads with +1 damage to Lead and DDT bloons. Twin Guns and Airburst Darts increase the attack speed of the reactor by ~17% and ~33% respectively. These upgrades will also apply the normal bonuses to the unsubmerged attacks.

Neither the attack damage nor cooldown bonus will stack for overlapping radiation zones of multiple Bloontonium reactors, but the pierce will. When overlapping with an Energizer, the Energizer attacks and cooldown bonuses will take priority.

It costs $2,125 on Easy, $2,500 on Medium, $2,700 on Hard, and $3,000 on Impoppable.

Behavior and Interactions[]

Bloontonium Reactor deals damage by creating a circular zone that uniformly applies damage to Bloons whose midpoints are within its range. Even large blimps like the BAD will not be damaged unless this condition is met. The radiation damage type is Shatter Shatter Type (pops Black, White, Purple, Frozen), meaning the reactor can pop all bloons including frozen bloons, but not Leads. Heat-Tipped Darts allows all reactor attacks to pop leads, thus changing that damage type to Normal Normal Type (pops Black, White, Purple, Lead, Frozen). It also increase lead bloons (including DDT ) +1 damage. In addition, the radiation damage can attack Camo Bloons before the Decamo pulse acts on a Camo Bloon. Regardless of crosspath, the decamo pulses occur have infinite pierce and are considered Universal Decamo Decamo, (MOAB-class bloons, unspecified alt variants), which allows it to decamo any bloon type.

When first switching between targetting options, the Bloontonium Reactor can attack directly after being set to submerge, or unsubmerge, allowing for extra damage to be squeezed in between attack pulses. But for subsequent switches in target priority, the radiation and regular dart attacks will not fire faster than their respective rates.

Other Notable Interactions[]

For a full list of all standard tower Interactions, click here.



The Bloontonium Reactor attacks by creating a circular zone of radiation that rapidly deals damage to large swathes of bloons while also removing the Camo property from Bloons and providing reduced ability cooldowns to water towers. Despite the submerged mode providing the bulk of the tower's usefulness, the unsubmerged attacks can also supplement small amounts of ranged damage. For these reasons, the Bloontonium Reactor excels in dealing with grouped bloon rushes for a relatively low price. Conversely, the Bloontonium Reactor is extremely weak in the role of single-target damage, struggling against Ceramics and MOABs. Furthermore, past round 80, Bloons become stronger, quicker and less dense, as Super-Ceramics, speed-ramped bloons, and high HP MOABs speed through the Bloontonium Reactor's irrelevant power. Another weakness is the restriction to water placement, often limiting the availability of strategic placements. In this way, the main use case for the Bloontonium reactor is for Race Events, early rounds, and as a stepping stone to the Energizer.

For early game and use in races, place the Bloontonium Reactor in water that is close to as much track as possible. Ideally, this section of track is consecutive, so regrow Bloons do not get a chance to regrow while exiting and reentering. Crosspathing is highly recomended as the 4-2-0 crosspaths allow Lead damage and higher pierce, while the 4-0-2 path allows for greater damage per second (DPS). Coupling these with a Beserker Brew or Stronger Stimulant is also an efficient way of garnering extra pops. In addition, stalling towers such as the Glue Gunner and Ice Tower further maximize the time the Reactor has to damage Bloons. If being used for the ability cooldown bonus and Decamo effect, shifting the sub towards water which can accomodate many neighboring towers is useful.

In gamemodes like CHIMPS, as well as general Late Game and Freeplay, the Bloontonium Reactor is generally a poor tower choice as it fails to provide the damage needed for dense MOAB rushes. In addition, the cooldown bonus is effectively useless as the Energizer provides a faster cooldown reduction that overrides all Bloontonium Reactors on screen.


  • There is almost no scenario where it would be beneficial to buy more than 1 Bloontonium Reactor. Multiple Reactors can not stack in the same area, and if being used for coverage of multiple paths, a cheaper long-range tower such as Hydra Rocket Pods would be more efficient.
  • Crosspaths for submerged Bloontonium Reactor are highly advisable. The middle path offers higher pierce and lead-popping power, where the bottom path allows for higher DPS.
    • On many occasions though, 4-0-0 is enough, as the tower doesn't do much damage in the late-game, and is mainly for reliable decamo and faster water-based ability cooldowns.
    • However, it's worth a note that a submerged 4-0-2 Bloontonium Reactor can solo regular bloons below Ceramic with ease, while support may be required to make it easier to pop the Ceramics or to damage Leads.
    • 4-2-0 may be superior over 4-0-2 against very dense rounds or on Race Events that enable Bloontonium Reactors, or just to deal with large weaker groups or pop Leads.
  • A submerged Bloontonium Reactor can decamo an infinite amount of bloons per decamo pulse. However, the radioactive attack itself only has a base pierce of 50. This can be increased to 70 with the Barbed Darts upgrade and 100 with Heat-Tipped Darts.
  • The submerged Sub's attack does not stack with other Subs in the radius.
  • If switching between Submerge and another targeting option at correct speeds, the Bloontonium Reactor can apply both attacks, increasing the overall DPS of the Reactor.
  • Submerging a Bloontonium Reactor has a very quick decamo pulse rate; it decamos bloons in range every 0.3 seconds, enough to decamo virtually any bloon passing by. When combined with Path 3 crosspathing, not only will this increase the decamo pulse rate, it will also increase the radioactive attack with it.
  • Using the Reactor to decrease ability cooldown of First Strike Capability allows for an easier double First Strike activation, especially on shorter maps or where the First Strike can only be bought very late.
  • Do note that using the Reactor as the main decamo tower may have issues on Round 100, where the BAD can pop at an unfavorable spot releasing DDTs that are not decamouflaged.
  • Due to the relatively quick attack rate, a submerged Bloontonium Reactor pairs well with Ice Shards when it comes to standard-bloon-popping power.

Version History[]

Overall, Bloontonium Reactor is stronger than it was compared to when it was first released. Not only was the pierce overall increased, it gained crosspath benefits to the submerged attacks, more specifically pierce for the Path 2 crosspath and attack speed for the Path 3 crosspath. Over time, however, the 4-2-0 Sub was given more buffs than 4-0-2, given current dominance of the attack speed path.

  • Buff Bloontonium Reactor pierce increased (30 → 70).
  • Buff Bloontonium Reactor has more range (50 → 52)
  • Buff 4-1-0 Submerged Reactor Sub gains 20% increased pierce from 70 → 84
  • Buff 4-2-0 Submerged Reactor Sub deals +1 damage to Leads
  • Buff 4-0-1 Submerge and Support Sub gains increased damage pulse rate (0.3s → 0.255s)
  • Buff 4-0-2 Submerge and Support Sub gains increased damage pulse rate (0.3s → 0.19125s)
As Bloontonium Reactor rarely uses up enough pierce that the pierce crosspath would ever matter, a large chunk of this has been moved into the middle crosspath.
~ Ninja Kiwi
  • Nerf 4-0-0 Bloontonium Reactor pierce decreased (70 → 50)
  • Nerf 4-1-0 Bloontonium Reactor pierce decreased (84 → 70)
  • Buff 4-2-0 Bloontonium Reactor pierce increased (84 → 100)
The logic on a Lead crosspath not being required to give Lead popping to an attack based on something weak against Lead has never sat right, so we're finally sorting that out and making sub a little angrier.
~ Ninja Kiwi
  • Nerf Bloontonium Reactor damage type changed from Normal Normal Type (pops Black, White, Purple, Lead, Frozen) to Shatter Shatter Type (pops Black, White, Purple, Frozen). Bloontonium Reactor now requires Heat-Tipped Darts to regain Normal damage type.


When changing to Submerge target priority:

  • [Sonar pulse]

When switching from Submerge to other priorities:

  • [Wave sound]


Official artwork[]

Status effects[]


  • In BTD5, the Bloontonium Reactor had infinite popping power. In BTD6, however, the damage pierce was reduced to 50 per pulse (or 30 prior to Version 2.0, or 70 pierce from Version 2.0 to Version 23.0).
  • Bloontonium Reactor may be a pun on the term Plutonium Reactor.
  • Prior to Version 29.0, Bloontonium Reactor could pop Lead Bloons regardless of crosspath, despite Lead being a popular shield against nuclear radiation in real life. Version 29.0 added this nerf to bring the middle crosspath into relevance.
  • Despite the radiant energy-like appearance of its attack, the Bloontonium reactor is able to pop Purple Bloons.