These special tanks safely contain the dangerous substance known as Bloontonium. Each tank can only support a limited amount. so smart monkeys build several. Fill the tanks with Bloontonium Generators, or by popping Bloons sent by other Monkey v Monkey players.
~ Bloons Monkey City Official Description

Bloontonium Storage Tank.png

The Bloontonium Storage Tank is a building in Bloons Monkey City. Each one costs $1000, occupies one square and stores Bloontonium Icon.png1000 for use in Monkey vs Monkey battles. They cost City Cash1000, take 20 minutes to build and give 500 XP once construction is completed. Level 8 is required to unlock (although Level 9 is required for Monkey vs Monkey).

They cannot be upgraded, so the only way to increase your Bloontonium capacity further is to build more of them. These buildings do not appear in the mobile version, as they are replaced by one single 2x2 building called the Bloon Inflation Factory.

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