Coral & Reef Keeping Glossary
Reef keeping has its own language. Whether you’re buying your first frag or dialing in an SPS-dominant display, this glossary explains the terms you’ll run into on our product pages and care tables — in plain English, from people who actually grow the coral. Pair it with our Acclimation & Dipping Guide →
A
Acclimation — The process of slowly adjusting a new coral to your tank’s temperature and water chemistry before adding it to the display. See our full guide.
Acropora — A genus of small-polyp stony (SPS) coral prized for fast growth and vivid color. Light- and flow-hungry, and the classic “advanced” coral. Browse our Acropora →
Actinic — Blue-spectrum aquarium lighting (around 420–460 nm) that drives coral fluorescence and makes colors pop. Most WYSIWYG photos are shot under actinics.
Alkalinity (dKH) — A measure of the water’s carbonate buffering capacity. Critical for stony coral skeleton growth; keep it stable at 8–9 dKH.
Aquacultured — Coral grown in captivity rather than collected from the wild. It’s hardier, already adjusted to aquarium conditions, and sustainable. All of our coral is aquacultured on our Key West farm under FL Aquaculture Cert #AQ0254072.
C
Calcium (Ca) — A key element corals use to build their skeletons. Target 400–450 ppm.
Chalice — A group of encrusting LPS corals loved for wild color combinations and “eye” patterns. Moderate light and flow. Browse our Chalice →
Coral dip — A short chemical bath (e.g., Coral Rx, Bayer) that removes pests and parasites from a new coral before it enters your tank. Always dip. Always rinse after.
Colony — A larger, mature coral made of many polyps, versus a small cut piece (frag).
D
dKH — “Degrees of carbonate hardness,” the common unit for alkalinity.
DOA — “Dead on arrival.” Rare with aquacultured coral shipped overnight, but covered by our live arrival guarantee.
Dosing — Adding supplements (calcium, alkalinity, magnesium, trace elements) to replace what growing coral consumes.
E
Encrusting — A growth habit where coral spreads as a thin sheet over rock rather than branching upward. Common in Montipora, chalice, and cyphastrea.
F
Frag — A fragment: a small piece cut from a larger coral colony, usually mounted on a plug or disc. The affordable way to start a new coral.
Fragging — The act of cutting a coral to propagate it. How coral farms (like ours) grow stock sustainably.
Flow — Water movement in the tank. Corals need it to bring food and carry away waste; requirements vary by species (see each product’s care table).
L
LPS — “Large-polyp stony” coral (e.g., scoly, acan, blasto, hammer, torch). Fleshy, forgiving, colorful, and great for beginners and pros alike. Browse our LPS →
Live rock — Porous rock colonized by beneficial bacteria and life; the biological filter of a reef tank. We stock Keys live rock in-store.
M
Magnesium (Mg) — An element that keeps calcium and alkalinity in balance. Target 1300–1400 ppm.
Montipora — A hardy, fast-growing SPS genus available in encrusting, plating, and branching forms. A great “first SPS.” Browse our Montipora →
Mushroom (Discosoma / Rhodactis / Ricordea) — Soft, disc-shaped corals that are among the easiest to keep. Low light and flow.
N
Nitrate (NO3) — A nutrient corals need in small amounts. Keep it in the 2–10 ppm range — not zero.
NPS — “Non-photosynthetic” coral that must be fed rather than relying on light. Beautiful but advanced.
Nudibranch — A type of sea slug; some species are coral pests (e.g., zoa-eating nudis) that a proper dip helps catch.
P
PAR — “Photosynthetically active radiation,” a measure of usable light intensity reaching the coral. Different corals want different PAR (listed on each care table).
Palytoxin — A potent toxin carried by some zoanthids and palythoas. Wear gloves and eye protection when handling and fragging. Never boil rock with zoas on it.
Phosphate (PO4) — A nutrient; keep low but present (0.03–0.10 ppm). Zero nutrients can starve coral and cause pale color.
Placement — Where a coral goes in the tank (high/low, light/shade, flow). Our care tables give a starting point for every piece.
Polyp — The individual living unit of a coral. “Polyp extension” (PE) is a good sign of a happy coral.
R
Ricordea florida — A jewel-like mushroom coral native to the Florida Keys. We’re licensed by the State of Florida to collect native species like this.
R/O & RODI — Reverse-osmosis (deionized) water: purified water used to mix saltwater and top off evaporation. We sell premixed salt and RODI water in-store.
S
Salinity — The salt concentration of your water, measured as specific gravity. Reef target: 1.025–1.026.
Scoly (Scolymia / Homophyllia) — A single-polyp LPS coral famous for intense color and pattern; a collector favorite. Browse our WYSIWYG pieces.
SPS — “Small-polyp stony” coral (e.g., Acropora, Montipora). Builds hard skeletons, wants strong light and flow and stable chemistry. Browse our SPS →
Soft coral — Corals without a hard skeleton (e.g., leathers, mushrooms, zoas). Generally the easiest to keep. Browse our Soft Coral →
W
WYSIWYG — “What You See Is What You Get.” The exact coral in the photo is the one you receive — not a stand-in. Our specialty; our photography is shot under actinics so what arrives matches the picture. Browse our WYSIWYG →
Z
Zoanthid / Zoa — Colorful colonial soft corals (“zoas” and “palys”) that grow in mats of button-like polyps. Easy, popular, and endlessly collectible — handle with gloves (see palytoxin).
Zooxanthellae — The symbiotic algae living inside coral tissue that photosynthesize and feed the coral. Lose them (from stress or heat) and the coral “bleaches.”
Still stuck on a term? We’re a real coral farm in Key West and happy to talk reef. Contact us → or read the Acclimation & Dipping Guide →