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

Bloontonium Reactor is the fourth upgrade of Path 1 for the Monkey Sub in Bloons TD 6. It emits a radioactive attack with 52 range that deals 1 damage every 0.3 seconds to up to 50 bloons while submerged (51 with NavalUpgradesIcon.png Naval Upgrades MK). 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 water tower ability cooldowns 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 total 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 other Bloontonium reactors, but the pierce will. When overlapping with an Energizer, the Energizer attacks and cooldown bonuses will take priority.

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



Submerged and unsubmerged Bloontonium Reactors

Bloontonium Reactor changes the submarine into a fully enclosed black submarine, presumably a nuclear submarine powered by Bloontonium. The submarine's backside and front both feature green radioactive symbols, oriented such that the pointy ends point towards the submarine's telescope. When submerged, nearby water glows with the color of the radiation, and regularly generates sonar scans that visually animate at the same rate as Submerge and Support. Normally, the glowing radiation from the nearby water and sonar scans are colored green, but with the 4-2-0 crosspath, they are colored red.

When crosspathed with Barbed Darts or Heat-tipped Darts, the telescope lens becomes red, and with Heat-Tipped Darts the front of the submarine's body around the radioactive symbol is given a red paintwork. Crosspathing with Twin Guns or Airburst Darts adds a pair of guns to the submarine, while Airburst Darts adds a yellow paintwork to the back sides of the submarine.


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 15% reduced ability cooldowns to water towers. The radioactive zone attacks every 0.3s (0.255s with 4-0-1 or 0.191s with 4-0-2), and have 50 pierce (70 with 4-1-0, 100 with 4-2-0). The decamo portion of the radioactive zone has 100 pierce (+20 with 4-1-0 or +50 with 4-2-0) and the attack speed of such is tied to the radioactive zone attack. The base range of that radioactive zone matches the base range of the Sub, at 52.

Crosspathing plays a major role in a submerged Bloontonium Reactor's overall popping power. Path 2 crosspaths increase pierce by +30 and +20 respectively, stacking additively for 70 and 100 pierce. Path 3 crosspaths reduce attack cooldown of the radioactive attack by a multiplier of 0.85x and 0.75x respectively, giving an extra ~17% and ~33% attack speed respectively, and stacking multiplicatively for a total of ~17% and ~57% bonus attack speed.

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.

An unsubmerged Bloontonium Reactor operates exactly like a Sub without submersion. Crosspaths alter an unsubmerged Sub's dart attack, giving normal bonuses.

Targeting Priorities[]

Bloontonium Reactor targets bloons using the standard targeting priorities, but also receives the Submerge targeting option. Its main attack while unsubmerged shoots straight movement projectiles that can moderately seek at bloons.

  • Submerge: Submerges the submarine, letting it create only submersible attacks instead of its other attacks. Initially gains only decamo, but can also gain additional benefits upon upgrading. When given Bloontonium Reactor or Energizer, the submarine gains an AoE effect that decamos and pops bloons.
  • First: Targets the first bloon visible within its range.
  • Last: Targets the last bloon visible within its range.
  • Close: Targets the closest bloon visible within its range.
  • Strong: Targets the strongest bloon visible within its range.

The radioactive attack is considered a zone-based attack, and pierce calculations default on Close. The local buff targets towers that are on water, and is considered a tower buff.


Updated as of Version 32.0. Listed prices exclude external buffs, any sacrifices, and Monkey Knowledge.
Purchase Sell
Costs Easy Medium Hard Impoppable Easy Medium Hard Impoppable
Upgrade (4-X-X) $2,125 $2,500 $2,700 $3,000 -
Total (4-0-0) $3,360 $3,955 $4,270 $4,745 $2,352 $2,769 $2,989 $3,322
Crosspath (4-1-0) $3,740 $4,405 $4,755 $5,285 $2,618 $3,084 $3,329 $3,700
Crosspath (4-2-0) $3,995 $4,705 $5,080 $5,645 $2,797 $3,294 $3,556 $3,952
Crosspath (4-0-1) $3,740 $4,405 $4,755 $5,285 $2,618 $3,084 $3,329 $3,700
Crosspath (4-0-2) $4,590 $5,405 $5,835 $6,485 $3,213 $3,784 $4,085 $4,540

This upgrade's prices (or included crosspath's prices) are affected by the following MK: MilitaryConscriptionIcon.png Military Conscription, AdvancedLogisticsIcon.png Advanced Logistics, BetterSellDealsIcon.png Better Sell Deals

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 Type (pops Black, White, Purple, Frozen) Shatter, 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 Type (pops Black, White, Purple, Lead, Frozen) Normal. It also deals +1 damage to lead bloons (including DDT ). In addition, the radiation damage can attack Camo Bloons before the Decamo pulse acts on a Camo Bloon. The decamo pulses are considered Decamo, (MOAB-class bloons, unspecified alt variants) Universal Decamo, 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 is a solid support tower and decent zone damage dealer to most bloon types. On maps with water pools that give it adequate track coverage, the Reactor can be a very reliable decamo tower. Reducing ability cooldowns on nearby water towers is a nice added bonus. Conversely, the Reactor has extremely weak single-target damage. It is not built to damage Ceramic and MOAB-class bloons. As a result, the Bloontonium Reactor excels at Race Events, early rounds, and acts as a stepping stone to 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 continuous, so Regrow Bloons do not get a chance to regrow while exiting and reentering. Crosspathing is highly recomended as the 4-2-0 crosspaths provides Lead damage and higher pierce, while the 4-0-2 path allows for greater 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 away from land where can accomodate many neighboring water towers is useful. It does not need maximum track coverage to ensure that no camouflage is left untouched.

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 rendered obsolete once the Energizer is bought. Its improved local and global buff effects override the tower buff of 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 advised. 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 does not do much damage in the late-game, and is mainly for reliable decamo and faster water-based ability cooldowns.
    • However, 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 a very high amount of bloons per decamo pulse, 100 by default plus up to +50 with 4-2-0. 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.
  • 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.
  • The limited decamo pierce shouldn't matter in any situation other than Race Events.

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.
Similar types of camo reveal like Shimmer/Signal Flare/Embrittlement are all pierce limited, but the Submerge sub has practically infinite pierce while also being extremely cheap with a very fast rate and a T4 that is far better at camo removal than those other towers can reach. Giving this upgrade a more reasonable pierce value brings these more in line and allows for the pierce crosspath to have some potential meaning.
~ Ninja Kiwi
  • Nerf 4-0-x Bloontonium Reactor decamo pulse pierce reduced infinite to 100
  • Nerf 4-1-0 Bloontonium Reactor decamo pulse pierce reduced infinite to 120
  • Nerf 4-2-0 Bloontonium Reactor decamo pulse pierce reduced infinite to 150


When changing to Submerge target priority:

When switching from Submerge to other priorities:


Official artwork[]

Status effects[]


  • Bloontonium Reactor may be a pun on the term Plutonium Reactor.
  • Despite the radiant energy-like appearance of its attack, the Bloontonium reactor is able to pop Purple Bloons.

Balance Changes (Trivia)[]

  • 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).
  • 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.