[Melody]

I apologize if some of these are repeats.

AC - Activated carbon, chemical filtration media / alternating current
Acro - Acropora, a type of SPS coral
AFAIK - As far as I know
ALK - Alkalinity, measure of buffering capacity of water
ASAP - As soon as possible
ATC - Automatic temperature compensating, a feature on some refractometers
ATM - At the moment
ATS - Algae turf scrubber, reef setup technique
Bfly - Butterflyfish
BOD - Biological oxygen demand
BTA - Type of anemone (Entacmaea quadricolor) / bubble-tipped, bulb tentacle, bulb tip
BTW - By the way
Ca - Calcium
CaCl2 - Calcium chloride
CaCO3 - Calcium carbonate
Ca(OH)2 - Calcium hydroxide
CC - Crushed coral / Counter current, type of protein skimmer
Cl - Chlorine
CO2 - Carbon dioxide
CO3 - Carbonate
CTA - Cellulose triacetate, type of RO membrane
Cu - Copper
CYANO - Cyanobacteria
DD - Downdraft, type of protein skimmer
DE - Double ended metal halide metal bulb
DI - Deionization, type of water purification
DIY - Do it yourself
dKH - Degrees of carbonate hardness, measure of alkalinity
DO - Dissolve oxygen
DOC - Dissolved organic carbon
DSB - Deep sand bed
DT's - Brand of refrigerated living phytoplankton
FAQ - Frequently asked questions
Fe - Iron
FO - Fish only, type of marine aquarium
FOWLR - Fish Only with Live Rock
Frag(s) - Broken or cut pieces of coral which will eventually grow into a new animal
Fuge - Short for refugium
FW - Freshwater
FWIW - For what its worth
FYI - For your information
FYM - For your misinformation
GAC - Granular activated carbon, chemical filtration media
GAL - Gallon
GBR - Great Barrier Reef
GFCI/GFI - Ground fault circuit interrupter / Ground fault interrupter
GPH - Gallons per hour
GOB - Green open brain
GSP - Green star polyps
HCO3 - Hydrogen carbonate
HD - Home Depot
HID - High intensity discharge, type of light
HO - High output fluorescent light
HOT - Hang on top, type of skimmer
HPS - High pressure sodium, type of light NOT for reefs but the ballasts concern them
HQI - High quartz iodide, type of light
HSA - High speed aeration, type of proteins skimmer
HTH - Hope this helps
I - Iodide
I2 - Iodine
ID - Identify/Identity
IIRC - If I recall correctly
IM - In my
IMCO - In my considered opinion
IME - In my experience
IMEO - In my expert opinion
IMHO - In my humble/honest opinion
IMNSHO - In my not so humble/honest opinion
IMO - In my opinion
IO - Instant Ocean, brand of synthetic salt mix
IO3 - Iodate
IOW - In other words
IR - Infrared, type of light of longer wavelength than visible light
IRC - Internet relay chat
ISP - Internet service provider
JME - Just my experience.
JMO - Just my opinion.
K- kelvin (mechanism for measuring spectrum of lighting, should be labeled degrees K) / Potassium
KALK - Kalkwasser, German for calcium hydroxide solution or limewater
KI - Potassium iodide
KISS - Keep it simple stupid
L - Liter
LED - Light emiting diode
LFS - Local fish store
LHS - Local hardware store
LMAO - Laughing my *** off
LOL - Laughing out loud
LPS - Large polyped Scleractinian (stoney) coral
LR - Live rock
LS - Live sand
LT - Litre
LTA - Type of anemone (Macrodactyla doreensis) / Long tentacle anemone
MACNA - Marine Aquaria Conference of North America, held annually
MEQ/L - Milli-equivalents per litre, measure of alkalinity
Mg - Magnesium
Mg/L - Milligrams per litre
MH - Metal halide light
MJ - Maxijet
MM - Miracle Mud, method of aquarium filtration
MO - Mail order
MV - Mercury vapor, type of light
Na - Sodium
NaCO3 - Sodium carbonate
NaOH - Sodium hydroxide
NH3 - Ammonia
NH4 - Ammonium
NNR - Natural nitrate reduction, reef setup technique
NO - Normal output fluorescent light
NO2 - Nitrite
NO3 - Nitrate
NP - No problem
NRN - No reply necessary
NSW - Natural seawater or New Sea Water
O2 - Oxygen
OBTW - Oh by the way
ORP - Oxidation reduction potential, the ability to take or give electrons
OTOH - On the other hand
PAR - Photosynthetically active radiation, lighting quantity
PC - Power compact fluorescent light
pH - Measure of the concentration of hydrogen ions, equal to -log[H+]
PH - Powerhead, water pump
PITA - Pain in the @ss
PLS - Please
PO4 - Phosphate
Pods - Non-specific types of copepods, amphipods and such
POS - Piece of doodoo
PPL - People
PPM - Parts per million, equivalent to mg/l (milligrams per litre)
PUR - Photosynthetically usuable radiation, lighting quantity
PVC - Poly vinyl chloride, used for piping / plumbing
RO - Reverse osmosis, type of water purification
ROB - Red open brain
RO/DI - Reverse osmosis, followed by deionization, type of water purification
ROFL - Rolling on the floor laughing
ROFLOL - Rolling on the floor laughing out loud
ROTFL - Rolling on the floor laughing
ROFLMAO/ROTFLMAO - Rolling on the floor laughing my *** off
ROTFLOL - Rolling on the floor laughing out loud
RR - Reef ready, aqaurium with pre-drilled holes and overflows
RTN - Rapid tissue necrosis
RUGF - Reverse flow undergravel filter
SAL - Salinity
SCWD - Switching Current Water Director, type of wave machine
SD - Southdown, type of sand
SE - Single ended, lighting designation
SG - Specific gravity
SHO - Super high output fluorescent light, equivalent to power compact fluorescent
Si - Silicon
SiO2 - Silicon dioxide
SITD - Still in the dark
SO - Significant other
SPS - Small polyped Scleractinian (stoney) coral
Sr - Strontium
SW - Saltwater / seawater
TAR - Type of magnetic ballast / substance used to embed magnetic ballast coils
TFC - Thin film composite, type of RO membrane
TIA - Thanks in advance
TIC - Tongue in cheek
TTYL - Talk to you later
UGF - Undergravel filter
UV - Ultra violet, type of light of shorter wavelength than visible light
VHO - Very high output fluorescent light
W - Watts
WD ( W/D ) - Wet dry, method of aquarium filtration
WPG - Watts per gallon, lighting quantity
WYSIWYG - What you see is what you get
YGM - You've got mail
YMMV - Your mileage may vary