ARID N18 Pax Bellum Macroalgae/Chaeto Reactor (40-120 US Gal Sys)
ARID N18 Pax Bellum Macroalgae/Chaeto Reactor (40-120 US Gal Sys)
ARID N18 Pax Bellum Macroalgae/Chaeto Reactor (40-120 US Gal Sys)
ARID N18 Pax Bellum Macroalgae/Chaeto Reactor (40-120 US Gal Sys)
ARID N18 Pax Bellum Macroalgae/Chaeto Reactor (40-120 US Gal Sys)

ARID N18 Pax Bellum Chaeto Reactor


40-120 US Gallon Systems

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The concept of using macroalgae/chaeto as a method of nutrient export is not new. However, the introduction of the ARID (Algae Remediation Illuminated Device) the original, patented macroalgae reactor by Pax Bellum is a quantum leap forward. This ingenious device utilizes macroalgae (specifically Chaetomorpha) to function as a tunable nutrient export mechanism. The unique design of the ARID incorporates a coaxial LED light tube to maximize light penetration and efficiency.

The tube and flange design of the device serves to isolate the algae from atmospheric CO2, which effectively limits the carbon source for the algae to only that which is respired by organisms within the aquarium. This is a self regulating feature and eliminates organic carbon buildup (yellowing of the water). The ARID is analogous to a lung for the aquarium, by supersaturating the aquarium with oxygen created by the algae during its respiration while removing excess CO2. Pax Bellum recommends running the ARID on a “reverse daylight” cycle (i.e.; opposite of the display aquarium) which helps to balance the natural day/night pH swing that occur, and to maintain high dissolved oxygen levels throughout the night when the display aquarium lighting is off and photosynthesis has ceased.

The ARID is capable of Targeting Specific Nutrient(s) for Export. In the reef aquarium the main concern is balancing the nutrients N:P:K:C, with the goal of limiting phosphate (P). Usually never in short supply, Potassium (K) and carbon (C) are not dosed. However, Nitrogen (N) can become depleted rapidly by the growth of algae, causing growth to stall. To keep the algae growing, the aquarist should dose the, “Nitrogen+Molybdenum” solution that came with the ARID reactor, at a rate to maintain the ratio of NO3 to PO4 at a minimum of 20:1 and ideally at 100:1 (example; 3ppm NO3 to 0.03ppm PO4). Maintaining this ratio will allow the Chaetomorpha or macroalgae of choice to continue to grow until phosphate levels reach the minimum cut off for growth at 0.02ppm.

Use the ARID with the Triton Method: One of the reasons we love this product is due to the fact that it is satisfies the need for the algae component when running the Triton Method. This method relies heavily on algae as the heart of the filtration system. Nutrients, namely NO3 and PO4 are largely kept in check by an algae component roughly 15-20% of the system volume. For aquarists that currently lack the space or ability to incorporate a large algae filter in their existing or new setup, this upright, sealed unit offers an excellent alternative. Because of the fast growing nature of Chaetomorpha algae especially in this reactor, we recommend placing it in the upper half, if placing other algae in the same unit.

Use the ARID with a Calcium Reactor and purchase the Ca injection assembly. This compact manifold threads directly into the water inlet on the base of the ARID N24, C30, C36 and inline with tubing on the N18. The assembly can be installed or removed at any time by the aquarist. This optional kit sends water directly to a Ca reactor or peristaltic pump supplying the Ca reactor, and receives effluent from the Ca reactor. This is accomplished by separating the high and low pressure ports by a user preset valve. The effluent coming from the calcium reactor passes through the included drip counter, and then enters the low pressure side of the calcium injection assembly where it mixes with the bulk of the water entering the ARID, making contact with the macro-algae where it is stripped of excess CO2 and PO4 before entering the reef system. This optional kit can increase the growth rate of your macroalgae and with it the nutrient uptake rate and dissolved oxygen production.

This unit comes with starter solutions 30ml Fe+Mn and 125ml N+Mo. Algae and Pump are not included.

Quick Disconnects not included. To add INLINE Quick Disconnects that will work with this factory 1/2″ tubing please purchase the ARID N18 Inline Quick Disconnect Set.  If you wish to upgrade to 3/4″ tubing you can install the ARID N24 Quick Disconnect Set.

Recommended size Aquarium: 40-120 US gal.
Recommended Flow Rate: 150-200 gph
Chamber Material: Cast Acrylic, features integrated hang-on bracket
Footprint: 6.5”
Height: 16.375″
Inlet/Outlet port size: 1/2″ FNPT
Power consumption: 13 Watts (The included power supply can accept 90-240vac, 50/ 60hz input. Swapping power cords allows this reactor to work worldwide, ask about country specific power cords)


1000 mls, 125 mls, 250 mls, 500 mls

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