hob : hang on back filter
no3, trates: nitrate
po4: phosphate
lr: live rock
ls: live sand
doc: dissolved organic carbon
fowlr: fish only with live rock
ato: automatic top off
ats: algae turf scrubber
lns: low nutrient system
ulns: ultra low nutrient system
sps: small polyp stony
lps: large polyp stony
softy: zoas and other soft coral
gha: green hair algae
dinos: dinoflagellates
h202: peroxide
big 3: alkalinity, magnesium, calcium
alk: alkalinity
mag: magnesium
cuc: clean up crew
gac: granular activated carbon
gsp: green star polyp
acro: acropora (an sps)
gfo: granular ferric oxide (removes po4)
all i can think of but itll get you going