Setting Up a Marine Aquarium

Steps to start a marine aquarium: mixing salt water, adding live rock, cycling the tank, protein skimming and the order in which to add livestock.

Overview

Setting up a marine aquarium means preparing salt water, establishing biological filtration and cycling the tank before any animals are added. The process rewards patience, as rushing the early stages is a common cause of failure.

Mixing salt water

Marine water is made by dissolving a synthetic sea salt mix in purified water, typically reverse osmosis or RO/DI water, until the target salinity is reached. A common target is a specific gravity of about 1.024, with fish-only systems often run around 1.020-1.024 and invertebrate systems around 1.023-1.026. Salt is usually mixed in a separate container and measured with a hydrometer or refractometer before use.

Adding live rock

Live rock is the primary biological filter in many marine setups, hosting the bacteria that drive the nitrogen cycle. A common guideline is roughly 0.5 to 1 pound of rock per gallon. The rock also seeds the tank with beneficial organisms and provides structure and shelter.

Cycling the tank

Cycling establishes bacteria that convert ammonia to nitrite and then to nitrate. Die-off from newly added live rock typically produces enough ammonia to start this cycle, so adding fish to speed it up is unnecessary and inhumane. Cycling commonly takes several weeks, often around six weeks, and is complete when ammonia and nitrite read zero and nitrate begins to accumulate.

Protein skimming

A protein skimmer removes dissolved organic compounds before they break down. It works by foam fractionation: fine air bubbles run through a column of tank water, dissolved substances such as proteins attach to the bubbles, and the resulting foam carries the waste out of the system.

Order of adding livestock

Livestock is added gradually after cycling, generally once the tank has run for around six weeks or more. A common approach is to add hardy invertebrates first, then begin adding fish after the system has been stable with invertebrates for about a month. New animals are acclimated slowly, for example with the drip method, to avoid osmotic shock.