Supernatant is the clear solution on top of a mixture. With kalkwasser, only the supernatant goes in the tank, never the white sediment.

Carbonic acid forms when carbon dioxide reacts with water. In a reef tank it's why extra CO2 at night or from respiration pulls pH down.

Bound phosphate is phosphate locked up with calcium, often on live rock. Standard tests can't see it, so a tank can read low and still have problems.

NPS corals are non-photosynthetic corals. They don't feed from light the way LPS and SPS corals do, so they depend on what you feed them.

TPS is the Aqua Care Guide's shorthand for temperature, pH and specific gravity: the three major parameters of Step 1 in a reef tank.

False uptake is when a test makes it look like corals used an element, but it left the water another way, such as calcium bound by phosphate.

FOWLR means Fish Only With Live Rock: a saltwater aquarium with no corals. It has its own salt and parameter targets in the Aqua Care Guide.

The uptake ratio is the proportion in which a reef tank uses up elements. Our Step 4 and Easy Reefer® products are made to match it.

The ugly stage is the normal algae phase after a new reef tank cycles, while the system settles toward balance. It's expected and passes.

Calcite is a brittle crystal form of calcium carbonate. Corals should build their skeletons from aragonite, the same chemistry in a stronger structure.

CAM is short for calcium, alkalinity and magnesium: the three main parameters corals use to build strong aragonite skeletons in a reef tank.

A calcium reactor is a piece of equipment that dissolves calcium carbonate media using CO2-acidified water, continuously replenishing calcium and alkalinity in a reef tank. It’s a popular automated alternative to manual dosing for heavily stocked or coral-dense systems.

Adsorption is the process by which molecules or ions bind to the surface of a solid material rather than being absorbed into it. In reef aquariums, this principle drives filtration media like activated carbon and GFO, which pull dissolved organics and phosphate out of the water.

Calcium carbonate is the compound corals and other reef organisms form when they combine calcium and carbonate ions from the water. It’s the primary structural material behind coral skeletons, reef sand, and live rock, making it central to nearly every reef building process.

Activated carbon is a porous filtration media used to remove dissolved organic compounds, toxins, and discoloration from aquarium water. By binding unwanted molecules to its surface, it helps keep water clear, controls odors, and supports overall water quality in a reef system.

Acclimation is the process of gradually adjusting a new fish, coral, or invertebrate to your tank’s water conditions before introducing it to the display. Slowly matching temperature, salinity, and chemistry reduces stress and shock, giving new arrivals a much better chance of settling in successfully.

Absorption is the process by which one substance is taken up into the internal structure of another, rather than simply sticking to its surface. In a reef aquarium, this happens when gases dissolve into water or when compounds are drawn into the pores of live rock, sand, or coral tissue.

A nitrate remover is any product or method specifically designed to reduce nitrate concentration in aquarium water, ranging from specialized filtration media to biological denitrification approaches. It’s a key tool for ongoing nutrient control.

An anemone is a soft-bodied marine invertebrate closely related to corals, known for its stinging tentacles and, in many species, a well-known symbiotic relationship with clownfish. Like corals, many anemones host zooxanthellae for energy, but they require their own specific care considerations in a reef tank.

Carbon dosing is the practice of adding a liquid carbon source to feed bacteria that consume excess nitrate and phosphate in a reef tank. It’s a widely used nutrient export method that works on the same principle as biopellets, just delivered in liquid form.