Pax Bellum ARID N24 Macroalgae Based Bio FIlter (120-250 US Gal Systems) $749


Pax Bellum ARID N24 Macroalgae Based Bio FIlter (120-250 US Gal Systems) $749 is backordered. We will ship it separately in 10 to 15 days.

The concept of using macroalgae as a method of nutrient export is not new. However, the introduction of the ARID (Algae Remidiation Illuminated Device) by Pax Bellum is a quantum leap forward. This ingenious device utilizes macroalgae (specifically Chaetomorpha) to function as a 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 within the device serves to isolate the algae from atmospheric CO2, which effectively limits the carbon source for the algae to just that which is respired by organisms within the aquarium. The ARID is analagous to a human lung for the aquarium, in that the ARID supersaturates the the aquarium with oxygen from the algae created during its respiration. Pax Bellum recommends running the ARID on a "reverse daylight" cycle (ie; 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 to occur.

Use 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, we recommend placing it in the upper half if placing other algae in the same unit.  

As an option, you can order a CO2 injection port ( Ca Reactor Feed/Injection Assembly) to send excess CO2 from your calcium reactor right into the ARID, which further benefits the growth of macroalgae.


1) Carefully unpack all of the contents from the box and ensure that all the parts shown are present.

2) Locate the power supply,  power cable, and LED array. Plug the male end of the power supply into the female and of the LED array.

3) Plug the power cable into the power supply and the other end into a standard 110-220 volt wall receptacle. Check that all LEDs light properly.

4) Place the power supply close enough to the reactor so that it can be plugged into both a power receptacle and your ARID reactor. Ensure that the power supply is not close to an open water source and is protected from any water spray. Placing the power supply in an unsafe location can lead to permanent damage of your reactor's components.

5) Plumb your ARID reactor into your system. Your reactor requires 180-250 GPH of flow (a Maxi-Jet 1200 is recommended). Your ARID reactor should be plumbed with fittings that are no less than 1/2" ID. Your ARID reactor is designed with a bottom up flow pattern; connect feed pump to the bottom fitting of your ARID reactor using either flexible vinyl tubing or rigid PVC. Be sure that there are no blockages or obstructions. A ball valve can be used between these connections for precise water control.

6) While holding the armature over the body of the ARID reactor, add approximately 2-3 large handfuls of Chaetomorpha algae into the open segment of the armature. 

Using the plastic spiral wraps installed in the unit, wrap several small clumps of clean chaetomorpha around the spirals, pinching it so it holds in place. 

7) Carefully load the armature into the body of the reactor.

8) Check the surface of the body o-ring to ensure that it is clean of any debris or strands of algae.

9) Secure lid by twisting it clockwise until it stops. Tighten thumbscrew securely. CAUTION: Thumbscrews may break if over-tightened!

10) Connect flexible vinyl tubing to the output fitting on the lid and place other end into the sump. Ensure that the plumbing is secure and that there are no blockages.

11) Turn on the flow to reactor and check for leaks around o-ring.

12) Using a timer or controller, create a schedule for your ARID reactor's lighting system. The reactor should be on a "reverse daylight" schedule from that of your display aquarium. It is best if your reactor turns on 1 hour before the display tank lights turn off, and remains on 1 hour after they turn off. Be sure to plug the power supply into the timer or appropriate socket of your controller.


Recommended size Aquarium: 120-250 gal aquarium

Recommended Flow Rate: 180-250 Gph

Recommended Pump: Maxijet 1200

Body Material: Acrylic

Total footprint: 9.5" x 8.25"

Total Height: 23"

Inlet/Outlet port size: 1/2" FNPT

LED power consumption: 110v/ 20 watts.  (The supplied power supply can handle 220v input power with the use of a simple adapter cord to connect to the wall socket-  Mainly for European use)

Placement-  Designed to be placed next to the sump.  This unit should not be placed within the sump.