Everything you need to know about the Pax Bellum A.R.I.D., Part1
What is the ARID Reactor?
The ARID Reactor is an acronym for; Algae Remediation Illuminated Device. It is a specially designed life support system for use in aquariums and aquaculture.
What does the ARID do?
By harnessing photosynthesis the ARID biosorption system has the capability to drive down phosphate to levels required for vigorous SPS coral growth without the need to constantly buy and replace chemical media. This biological filtration system works on the principle of what Pax Bellum LLC likes to call "biological stoichiometry"; the balanced control of products and reactants in a biological system by use of a biological medium as a nutrient export, in this case algae and bio-film. Simply put, specific nutrient levels and ratios can be controlled with precision.
In addition, by running the ARID on a reverse daylight schedule to the display tank, pH and dissolved oxygen is kept at a higher level and stable over the 24hr cycle.
Being sealed from atmospheric gases the ARID is dependent on dissolved CO2, thereby keeping CO2 levels and organics to a minimum.
How is it any different from a refugium?
In the ARID system algae is the main nutrient export and to a lesser extent the bio-film forming on the algae surface. Twice a month the Chaetomorpha is vigorously rinsed of the bio-film clinging to its surface and up to 1/3 is harvested. In this way the ARID system differs from a refugium. Chaetomorpha is not viewed as a home for arthropods, copepods and the like it is simply used as biomass for the export of unwanted nutrients. The entire structure of the ARID reactor is geared to doing this task as efficiently as possible in the smallest footprint possible.
Even and rapid growth is all about the flow… In a refugium water flows around compacted masses of macro-algae, delivering nutrients only to the outer surface of the algae mass leaving dead zones within. Even worse flow is observed when Chaetomorpha is spun like in a pseudo-kriesel, where water velocity matches the spin velocity of the algae. Inevitably dead zones occur in the center of the mass.
In the ARID water and nutrients are forced through the interwoven macro-algae mass with a mixture of turbulent and laminar flow at constant velocity, eliminating dead zones and ensuring nutrient delivery and growth is even throughout the ARID reactor.
Illuminated from within, the ARID uses a coaxial LED lighting array, evenly delivering light to the entire mass of macro-algae by the most efficient means possible. Light is not reflected off a water surface like with a refugium. The light is contained by the ARID’s chamber walls that act as reflectors bouncing any light that makes it through to the outer wall wall back into the algae.
How is this different from an Algae Turf Scrubber (ATS)?
Algae Turf Scrubbers (ATS’s) come in all shapes and sizes. ATS’s are usually rectangular acrylic boxes housing a vertically oriented screen or a plurality of screens and a LED array or other light source(s) that can evenly illuminate the entire grow surface of the mesh the turf algae grows upon. They grow turf algae, hair algae, aka Bryopsis species using a nutrient film technique.
The hair algae suspended in air on the mesh has unlimited access to atmospheric CO2, which does allow for rapid growth but much of the captured carbon it converts into sugars leaks into the system water, leading to organics buildup.
Their design is probably unintentionally similar to an evaporative cooler, aka swamp cooler, evaporating a good deal of aquarium system water daily. Most of the cooling effect is lost to the heat put in by the large array of lights. But they may contribute a cooling effect if you live in a dry hot climate. The trade off is making up more R/O water to replace the evaporation.
Any oxygen produced by the turf algae is mostly lost as it interacts with the water surface before returning to the system. Likewise effluent from a calcium reactor is not as easily attached to the intake of an ATS. And when is the last time a local fish store gave you money for hair algae? They often will for Chaetomorpha.
I use Granular Ferric Oxide (GFO), why should I switch to running the ARID?
Granular Ferric Oxide (GFO) is a chemical media used in a fluidized reactor used by aquarists to bind phosphate, and It does this job very well. GFO also binds other metals we call trace elements, necessary for healthy aquarium systems. GFO has its place in the aquarist tool box but like antibiotics shouldn’t be used only when necessary.
GFO can be difficult to judge how much you need to bring down X amount of phosphate. Add too much and corals get stressed, or worse cause a crash. Ideally GFO is used in small amounts and changed out often, since the PO4 absorption curve is not linear. The aquarist becomes locked into a constant pursuit of PO4 readings. And really who wants to deal with this granular mess. Cost is another factor, constant expenditure on media adds up over time. The reactors are cheap for a reason, to get people hooked.
GFO also does nothing to control nitrate. Worse, by removing PO4, organisms in the tank are not able to uptake, or denitrify the NO3 as quickly.
I heard I don’t necessarily need a skimmer when running the ARID?
Let your aquarium breathe easy, you don’t need a skimmer to oxygenate your aquarium water. The ARID produces oxygen for your aquarium. A skimmer can only equilibrate the O2 and CO2 levels to that of the surrounding room, a room that is often much higher in CO2 levels than found above a natural reef. CO2 can be scrubbed out of the air being drawn into the skimmer with the use of chemical absorbents, but again that’s another canister and media to deal with. While the ARID is capable of supersaturating the aquarium with O2 while absorbing CO2 much like phytoplankton does in the surface waters of the ocean. Algae’, using photosynthesis splits water molecules to produce oxygen, and absorbs CO2 to produce stores of sugars for energy.
Let your aquarium harness this gas production and absorption bio-machinery by running the light cycle of the ARID reverse to your tank lighting. Running a reverse daylight cycle will balance the usual day/night pH swing by maintaining dissolved oxygen high, and CO2 levels low throughout the night when your reef aquarium lights are switched off, and photosynthesis by corals has ceased.