Kelp Growth in a Tank

Kelp grows in areas of the ocean where sunlight is able to penetrate to the rocky sea bottom. This fast growing marine plant attaches to the ocean floor with its holdfast and grows up toward the surface. Kelp requires both strong light and nutrients to thrive. Under natural conditions, kelp continues to grow once it reaches the ocean surface and forms extensive floating mats. Provided there is strong lighting and nutrients, this interesting aquatic plant grows very well in marine aquariums.

  1. Tall Aquariums

    • Aquarists interested in propagating kelp need a tall aquarium due to the height of these aquatic plants. Aquariums that are at least 36-inches tall are well suited for kelp growth. These aquariums require powerful circulation to take oxygen-rich water from the surface to the lower regions of the tank. Aquariums breathe through the surface water. Life-giving oxygen enters the water through the surface and carbon dioxide, which is toxic once it builds up in the water, dissipates from the surface water. These processes occur most effectively in shallow tanks, hence the need for strong circulation in a tall kelp aquarium.

    Suitable Fish Species

    • Both seahorses and pipefish inhabit kelp beds under natural conditions and aquarists can house these species in a kelp aquarium. Both of these fish species target tiny living crustaceans, such as brine shrimp, for a food source and do not graze on the kelp fronds. Kelp requires nutrients to grow optimally and the seahorses and pipefish readily supply the nutrients in the form of metabolic waste they release into the aquarium on a continual basis.

    Using a Sump

    • Certain aquarists want to culture kelp because it removes nutrients from the aquarium water and in this way, assists in keeping the water clean and chemically balanced. These hobbyists opt to place the kelp not into the display aquarium, but into their sump. The sump is a reservoir that is placed below the display aquarium, but connected to it by piping. Kelp that grows in the sump removes nutrients from the water but leaves space in the display tank for other marine organisms, such as living coral and sea anemones.

    Strong Light

    • Kelp grows under either metal halide bulbs or fluorescent tubes; the lighting should be rated at approximately four watts per gallon. Metal halide lamps give an intense light and create beautiful shimmer lines on the kelp and aquarium substrate, but give off a great deal of heat. They are typically suspended above the aquarium and not placed in the canopy. Kelp is a fast-growing aquatic plant and needs to be cut back on a regular basis to prevent it from overrunning the aquarium.