Deciphering Hobby Talk: Acronyms and Commonly Used Terms


We've all been there - the daunting reply to a thread in which every other word is an acronym or a term that everyone else but you seems to understand. Here is an attempt to clear up and define some more of the commonly used terms in the hobby and on the forums. Ive searched through the forums and combined some of the older acronym lists that have been buried and included some of the more current terminology as well as chemical formulas, coral names, people, vendors and treatments that are commonly seen on Reef2Reef. This alphabetical list should make it much easier to navigate the lingo for beginners and seasoned veterans alike!


A / Amp – Ampere. A measure of electricity
AA - Amino Acid
ABT - Atlantic blue Tang
AC - Activated Carbon
AC - Alternating Current
Acan Lord – Acanthastrea coral, scientific name: Micromussa lordhowensis
Acro- Acropora coral

AcroASD (1).jpg

AEFW - Acropora Eating Flatworms
AGA - All-Glass Aquarium
AIO – All in One – typically in reference to an aquarium
Alk – Alkalinity
Alkalinity - The measure of carbonate (HCO3) and bicarbonate (H2CO3) in solution
Algae Reactor – A media reactor filled with macro-algae (generally Chaetomorpha) and wrapped in LED lights in order to speed growth and nutrient removal. This is essentially a type of refugium
Apex – A popular aquarium controller made by Neptune Systems
Aquacultured – A coral/fish that has been grown in captivity, rather than in the ocean
ASW – Artificial Sea Water
ATC – Automatic Temperature Compensation
ATO - Auto Top Off
ATS - Algae Turf Scrubber
Aussie – Slang for coral gathered in Australian waters


BA - Bubble algae (Valonia ventricosa)


BB - Bare Bottom
BBT – Bare Bottom Tank
BC – BattleCorals (.com)
Bean / Beananimal – A drain set up with three stand pipes, one at full siphon, one open channel and an emergency drain
Big 3 – Refers to common parameters of a reef tank: Calcium, Alkalinity & Magnesium
Biofilter – Refers to the bacteria that converts ammonia into nitrite/nitrate/nitrogen in the aquarium
Biological Filtration – Refers to the nitrifying bacteria within an aquarium that breaks down waste into less harmful by products. Can also refer to macroalgae filtration, deep sand beds, carbon dosing and/or biopellets.
BioWheel – A cylinder of filter media that is generally a part of a hang on back filter to host bacteria
Blasto – Blastomussa. Blastomussa is a genus of large polyp stony corals. Some members of this genus are sometimes found in reef aquariums
Bleaching – Refers to the loss of coloring pigments in corals, generally due to undesirable lighting or nutrient levels
BLC – Blue Legged Hermit Crab
BOGO - Buy One, Get One (Free). A term used in sales of livestock
Bonded Pair – Refers to a pair of fish that have paired off into a male/female pair. These may not yet be of breeding age
BR – Base Rock
BRS – Bulk Reef Supply
BTA – Bubble Tip Anemone
BTU - British Thermal Unit


C2C – Coast to Coast Overflow
Ca – Calcium
CaCl2 – Calcium Chloride
CaCO3 – Calcium Carbonate
Ca(OH)2 – Calcium Hydroxide
CaRx – Calcium Reactor
Cali – California
CB – Cornbred a well-known coral vendor/propagator
CBB - Copper Band Butterfly


CC - Counter Current
CC - Crushed Coral
CFL - Compact Fluorescent Lamp
CH – Carbonate Hardness
Chaeto – Chaetomorpha. A macro algae
CL - Closed Loop
CL - Craigslist
CO2 - Carbon Dioxide
Colony – An aggregate of individual organisms, generally used to refer to a number of coral polyps
Conductivity – A measure of a solutions ability to conduct electricity. Generally used as a fast and reliable way to measure the ionic content in the solution. The conductivity of reef tank water is not equal to the salinity of the same water.
Cooking – Typically a slang term used to describe a method of soaking rock to leech off any unwanted or undesirable compounds (such as Phosphates) or detritus. It generally does not refer to literally cooking rocks.
CP – Chloroquine Phosphate, a medication used to treat Ich and Velvet
Crypto – See Ich
Cu - Copper
CUC - Clean Up Crew
CWC - Continuous water change
Cyano – Cyanobacteria. Cyanobacteria are a group of photosynthetic, nitrogen fixing bacteria that live in a wide variety of moist soils and water
Cycle – Typically refers to establishing the nitrogen cycle in conjunction with starting a new aquarium. We establish the nitrogen cycle, not end it


DC - Direct Current
DD - Downdraft
DD - Diver's Den - a specialize subset from that sells WYSIWYG items that go through a heightened quarantine and acclimation. Often are harder to find fish/corals/invertebrates
DE - Double Ended
Detritus - Dead particulate organic material (as opposed to dissolved organic material). It typically includes the bodies or fragments of dead organisms as well as fecal material. Detritus of aquatic ecosystems is organic material suspended in water and piles up on seabed floors
DFS - Drs. Foster and Smith
DI – Deionization
DI water - Deionized water
Digi – Montipora digitata
Dinos – Dinoflagellates
Dirty – Generally referring to high nutrient levels in an aquarium
DIY - Do It Yourself
dKH - German Degrees of Hardness, units used in alkalinity measurements
DO - Dissolved Oxygen
DOC - Dissolved Organic Carbon
Dory – Reference to the Disney movie “Finding Nemo”, Dory is a Paracanthurus hepatus – commonly called a hippo tang, blue tang, or palette surgeonfish
DSB - Deep Sand Bed
DT - Display tank
Durso – A type of drain system utilizing two stand pipes, one at full siphon and the other with an open channel.


EB – Electronic Ballast
EC – End Cap
ESV – A commonly used brand of Alkalinity and Calcium supplement
ETA - Estimated Time of Arrival
Eurobrace – A glass or acrylic brace that is attached to the top of an aquarium to structurally reinforce it



FB – Facebook
Fe - Iron
Feeler – A thread where the originator is asking for opinions on a selling price for an item
FO - Fish Only
Foot – Generally a term used in respect to anemones, this is the basal disc, or part that attaches to the rock or substrate
FOWLR - Fish Only With Live Rock
Frag - Fragment (a small part of a coral colony removed in order to grow another colony)
Frag Plug – A piece of ceramic, plastic or stone used in coral propagation. Frags are mounted on frag plugs
FTS - Full Tank Shot
FTW- For the win
Fuge - Refugium
FW – Freshwater
FWD – Freshwater Dip
FWE - Flat Worm Exit
FWIW -For what its worth


G- Gallon (ex. 60g)
GAC - Granular Activated Carbon
GBP – Green Button Polyps
GBR – Great Barrier Reef
GBTA - Green Bubble Tip anemone
GFCI - Ground Fault Circuit Interrupter
GFI - Ground Fault Interrupter
GFO - Granular Ferric Oxide
GHA - Green Hair Algae


Ghost Overflow – A style of overflow that has a minimal footprint inside of the aquarium with a larger overflow box on the exterior of the aquarium that houses the drain standpipes
GPD - Gallons per Day
GPH - Gallons per Hour
Group Buy – Generally a large number of people making a large order at one time to gain some discount or shipping benefit from a vendor
GSM -Gold Stripe Maroon Clownfish
GSP - Green Star Polyps
Guest – An organism that is hosted by another organism. Example: Clownfish are guests to the anemone.


H2O – Chemical formula for water
H202 – Chemical formula for Hydrogen Peroxide
HA - Hair Algae
HAB – Harmful Algae Bloom
Herbie – A drain setup with only one stand pipe, typically with a hole present to prevent a full siphon
HID - High intensity discharge
High Light – A generic term generally referring to the amount of lighting a coral needs to survive. High light is vaguely defined as a PAR measurement of 300+.
Hitch hiker – A term used for an organism that was introduced to the tank inadvertently, generally by live rock or coral frag plug
HITH – Hole in the Head Disease
HLLE – Head and Lateral Line Disease


HO - High Output
HOB - Hang on Back
Host - An organism that harbors a parasitic, a mutual, or a commensal symbiont, typically providing nourishment and shelter. Example: Anemones host clownfish
Hosting – The act of harboring a guest, generally to the mutual benefit of both the Guest and the Host. Anemones are hosting my clownfish pair.
HOT - Hang On Tank
HQI - Mercury (Hg) Quartz Iodide


I / I2 - Iodine
Ich / Ick – Cryptocaryon irritans is a species of ciliates that parasitizes marine fish, causing marine white spot disease or marine ich


ICP – Inductive Coupled Plasma. A type of mass spectrometry which is capable of detecting metals and several non-metals at very low levels. This is achieved by ionizing the sample with inductively coupled plasma and then sorting the resulting ions by mass spectrometry
IME - In my experience
IMHO - In my humble opinion
IMO- In my opinion
IO - Instant Ocean
IR - Infrared
IW - In Wall


JF – Jason Fox, a well-known coral vendor/propagator


K – Kelvin
Kalk – Kalkwasser. A German term for calcium hydroxide or saturated limewater. A method of supplementing alkalinity and calcium consumption in an aquarium
KISS – Keep It Simple Stupid
KWh - Kilowatt-Hour


L – Liter
LA – LiveAquaria (.com)
lb(s) - Pounds
LED - Light emitting diodes
Lepto – Leptoseris coral
LFS - Local fish store
LHS – Local hardware store
LMB – Lawnmower Blenny
LNS – Low Nutrient System
Lobo – Lobophyllia. Lobophyllia, commonly called lobed brain coral or lobo coral, is a genus of large polyp stony corals
Low Light – A generic term generally referring to the amount of lighting a coral needs to survive. Low light is vaguely defined as a PAR measurement of 100 or less
LPS - Large polyp stony corals that have large and soft polyps
LR - Live Rock
LS - Live Sand
LTA - Long Tentacle Anemone


Lymph – Short for Lymphocystis, a common viral infection in marine fish


MACNA - Marine Aquaria Conference of North America
Maricultured – Generally a coral that has been grown on a coral farm in the ocean
Macro – Macroalgae. Typically this refers to algae that form larger and more complex growth forms. Example: Chaetomorpha
Marine Ick – See Ich
Marine Velvet - Velvet disease, also called gold dust disease, is a fish disease caused by dinoflagellate parasites of the genus Piscinoodinium, which gives the fish a dusty, slimy look.
Marine White Spot Disease – See Ich
MASNA - Marine Aquarium Societies of North America
MB – Magnetic Ballast
MD – Marine Depot (.com)
Mechanical Filtration – A method of capturing floating debris from the water and removing it before it breaks down further. Generally these are filter socks and filter pads.
meq/L - Micro-equalities per Liter
Mg or Mag – Magnesium
mg/L – Milligram per liter
MH - Metal Halide light
Milli - Acropora millipora


Mini-Cycle – This is not a thing. See Cycle
Mixed Reef – Generally refers to an aquarium that contains SPS, LPS and Soft corals
MJ - Maxijet
Mr. Saltwater Tank – Mark Callahan, a YouTube personality with a web series devoted to the reefing hobby
MS – Mass Spectrometry
MV – Mercury Vapor
Mysis – A small freshwater shrimp that is widely used as frozen food for marine aquariums


N2 – Nitrogen
Na – Sodium
NACO3 – Sodium Carbonate
NaOH – Sodium Hydroxide
Nano Tank – A small aquarium, generally between 5 and 20 gallons in size
Nemo – A reference to the Disney movie “Finding Nemo”, Nemo is an Amphiprion ocellaris, commonly called a clownfish
Nems- anemones
Newbie – A person new to the hobby
NH3 - Ammonia
NNR - Natural Nitrate Reduction
NO - Normal Output
NO2 - Nitrite
NO3 – Nitrate
NOPOX - NO3PO4X is a Red Sea additive used for controlling nutrients.
NPS - Non Photosynthetic
NSA - Negative Space Aquascape
NSW – Natural Sea Water
NTS – New Tank Syndrome


O2 – Oxygen
OC – Open Channel. A drain tube that allows both water and air to enter.
OC – Original Collector
One Inch Per Gallon – An antiquated adage that are certain total inches of fish would be compatible with the total gallon size in an aquarium. This ‘rule’ is widely believed to be incorrect
ORA- Oceans, Reefs, and Aquariums
ORP - Oxygen Redox Potential
OTS – Old Tank Syndrome


PA – Premium Aquatics
PAR - Photosynthetic Active Radiation, a unit used in measuring light output
Paly – Palythoa coral
PB – Pulse Ballast
PBT-Powder Blue Tang
PC - Power Compact
PE – Polyp Extension (in relation to corals)
PE – Piscine Energetics (food company)
pH - The measure of the ratio of H+ to OH- ions in solution. Typical pH range in a reef tank is 7.8 – 8.2
PH – Power Head
Pico Tank – A small aquarium, generally less than 5 gallons in size
Pods – Refers to a variety of small crustaceans, generally copepods and amphipods

Tigriopus californicusMale.jpg

PO4 - Phosphate
POTM - Picture of the month
PP - Per polyp
PPM - Parts per Million
PPT - Parts per Thousand
Prazi – Prazipro, a commonly used deworming medication to treat flukes
Profilux – A popular aquarium controller made by GHL
PS – Protein Skimmer
PUR- Photosyntheically Usable Radiation, a unit associated with light measurement
PVC - Poly Vinyl Chloride


QM – Quality Marine
QT - Quarantine Tank


R2R - Reef to reef (.com)
RAP – Reef-A-Palooza, a large reefing conference
RBTA - Rose Bubble tip anemone
RC - Reef Crystals
RC – ReefCentral (.com)
RDSB - Remote Deep Sand Bed
Redfield Ratio - The atomic ratio of carbon, nitrogen and phosphorus found in phytoplankton and throughout the deep oceans. This empirically developed stoichiometric ratio was originally found to be C : N : P = 117:14:1
RHF – Randy Holmes-Farley, Reef2Reef resident chemist
Rics – Ricordea
Rimless – An aquarium that has no plastic or eurobracing around the top of the tank.
RK / RKL – ReefKeeper, a popular aquarium controller
RO water - Reverse osmosis water
RODI - Reverse Osmosis, Deionized
ROX – A specific type of activated carbon used to remove impurities from the water. Generally considered an aggressive type of carbon
RR - Reef Ready (aquarium)
RR – Reef Raft (corals)
RTN - Rapid Tissue Necrosis


RUGF – Reverse Under Gravel Filter


Sanjay – Refers to Sanjay Joshi, a well-known authority on reef lighting
SE - Single Ended
SG - Specific Gravity
Shrooms – Mushrooms
Si – Silicon
SiO2 – Silicon Dioxide
Socks – Filter socks, a type of mechanical filtration
Softy – Corals that lack a rigid calcium skeleton. Typically zoanthids, mushrooms, leathers and xenias
SPS - Small polyp stony coral
SSB - Shallow Sand Bed
Starphire – A low iron glass made by PPG
STN - Slow Tissue Necrosis
Stoichiometry - The calculation of relative quantities of reactants and products in chemical reactions.
SW - Salt Water / Sea Water


T5 / T8 – Reference to the size of fluorescent bulbs for aquarium lighting
Tank – An Aquarium
TBS – Tampa Bay Saltwater (.com)
TDS - Total Dissolved Solids
Texas Trash – See Green Button Polyps. Often seen as an undesirable and invasive coral
TFC - Thin Film Composite
TIC – Total Inorganic Carbon
TOTM - Tank of the month
Tort – Acropora tortuosa
Triton Test – An ICP analysis that shows a variety of metal and non-metal components in a sample of aquarium water. A sample of aquarium water is mailed to the testing lab and results are generally received in 7-10 days


TTM – Tank Transfer Method. A method of quarantining fish to prevent and cure some common parasites
Trachy – Trachyphyllia
Two Part – Refers to an additive system using 2 or more components to supplement calcium and alkalinity. Often can supplement magnesium as a “third” part
Tyree – Named after Steve Tyree, a well-known coral vendor/propagator


UGF – Under Gravel Filter
ULNS - Ultra Low Nutrient System
UPS – Uninterruptible Power Supply
UV - Ultra Violet


V - Volt
VHO - Very High Output (fluorescent light)
VSV – Vodka, Sugar and/or Vinegar


W - Watts
WC - Water Change
Wellso – Wellsophyllia


WPG – Watts per Gallon
WTB – Want to Buy
WTS – Want to Sell
WTT – Want to Trade
WQ – Water Quality
WWC – World Wide Corals
WYSIWG - What you see is what you get


YWG-Yellow Watchman Goby


Z&P - Zoanthids and Palythoa
Zoas - Zoanthid Coral
Zoos – Slang term for Zoanthids

About author
Kris Fulk has been keeping marine tanks for over a decade, and has been keeping aquariums for the better part of the last three decades. His current tank is a 100 gallon SPS tank running on the ZeoVit method. His real profession is a research chemist at a large pharmaceutical company, but he has degrees in marine biology (botany focus) and biotechnology. He describes himself as a "professional learner" and considers himself walking proof of Murphy's Law. Kris resides in Western Michigan with his wife, two children and two mastiffs.

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