Daily demand refers to the amount of a nutrient, food, or dosed supplement a reef tank’s organisms use up over a 24-hour period. Understanding daily demand helps reef keepers calibrate dosing and feeding routines to match actual, ongoing consumption.

Ammonia is a toxic nitrogen compound produced by fish waste, uneaten food, and decaying organic matter. As the first stage of the nitrogen cycle, even small amounts of ammonia can stress or harm fish and invertebrates, making it one of the most closely monitored parameters in a new aquarium.

A calibration solution is a reference liquid with a precisely known value, used to verify and adjust the accuracy of test equipment like refractometers, pH probes, and conductivity meters. Regular calibration helps ensure the readings a reef keeper relies on are actually correct.

Green hair algae is a common nuisance algae that forms thin, hair-like strands across rock and substrate, typically driven by excess nutrients. It’s persistent but generally manageable through nutrient control and manual removal.

Alkalinity consumption refers to the rate at which corals and other calcifying organisms use up alkalinity as they build their skeletons. Because this steady drawdown pulls alkalinity out of the water over time, tracking consumption helps reef keepers know how much to dose or supplement to keep levels stable.

Cyanobacteria, often called cyano, is a photosynthetic bacteria that forms slimy red, green, or dark mats across rock and sand in a reef tank. It typically signals excess nutrients or poor flow, and can spread quickly if left unaddressed.

Calcium uptake refers to the rate at which corals and other calcifying organisms draw calcium from the water to build their skeletons. Like alkalinity consumption, tracking calcium uptake helps reef keepers understand how much supplementation a tank actually needs.

Curing is the process of allowing newly acquired live rock or sand to stabilize before adding it to a display tank, letting any dying organic matter decompose safely elsewhere. It helps prevent ammonia spikes and other water quality problems in the main system.

An algae bloom is a rapid, often sudden overgrowth of algae in an aquarium, usually triggered by excess nutrients, light, or a lack of competition from other organisms. While a normal part of a young or shifting reef system, persistent blooms usually signal an imbalance that needs to be addressed.

The carbonate system describes the interconnected balance of dissolved CO2, bicarbonate, and carbonate in reef aquarium water. This equilibrium governs both pH and alkalinity, making it one of the most fundamental chemical frameworks underlying reef water chemistry.

Nitrogen is an essential element that cycles through a reef tank in various forms, from toxic ammonia to comparatively stable nitrate. Understanding nitrogen’s journey through the tank is foundational to managing water quality effectively.

Autotrophic feeding refers to the way many corals generate energy internally through photosynthesis, using the zooxanthellae living in their tissue rather than capturing external food. This process allows light-dependent corals to meet much of their energy needs directly from the tank’s lighting conditions.

A hydrometer is a simple, inexpensive tool used to measure a saltwater tank’s specific gravity, one way of estimating salinity. While easy to use, it’s generally considered less accurate than a refractometer or digital salinity meter.

Detritus is the accumulated organic debris in a reef tank, including uneaten food, waste, and decaying matter. While a normal part of any system, excess detritus can degrade water quality and fuel nuisance algae if not regularly managed.

Aragonite is a crystalline form of calcium carbonate and the primary material that makes up coral skeletons, reef sand, and live rock. As corals grow, they continuously deposit aragonite, making it one of the fundamental building materials behind a healthy, structurally sound reef.

Carbonate is an ion that, together with bicarbonate, makes up a reef aquarium’s alkalinity. It’s the form corals directly combine with calcium to build their calcium carbonate skeletons, making it central to both water chemistry stability and coral growth.

Nitrite is the second compound produced during the nitrogen cycle, forming as bacteria convert ammonia and remaining highly toxic to most reef organisms. Its presence typically signals an aquarium is still in the process of cycling.

Heavy metals are dense metallic elements, such as copper, lead, or mercury, that can be toxic to reef tank livestock even at very low concentrations. They typically enter a system through contaminated source water, equipment, or accidental exposure.

A deep sand bed is a thick layer of fine sand, typically several inches or more, used to support anaerobic bacteria that process nitrate through denitrification. It offers natural nutrient export alongside its role as habitat for burrowing organisms.

Growth limitation occurs when a coral’s growth rate is restricted by a lack of a specific necessary element or condition, even when other parameters are adequate. Identifying the limiting factor is key to resolving unexpectedly slow coral growth.