Articles

82 articles on reef aquaristics — from water chemistry to practical husbandry and scientific deep dives.

Basics

The biological and chemical fundamentals of reef keeping.

Saxby's principle — water comes first

Why reefkeeping is not about keeping animals but about keeping water, and what this means in practice.
RO/DI — the foundation of clean water

What Finnish tap water contains, why zero TDS does not mean clean water, how an RO/DI unit works and where its limits lie.
The stability principle — why consistency beats perfection

A single measurement vs. trend, the paradox of constant adjustment, one change at a time, and why predictability matters more than hitting a perfect target.
The cycling process — what happens before adding any animals

The basics of the nitrogen cycle, nitrification microbes and what actually happens biologically during the cycling phase.
Temperature — the invisible foundation of a stable reef

Why temperature is one of the most critical reef aquarium parameters, what the target range means in practice, and how temperature fluctuation affects corals.
Flow is a biological necessity

Why turnover rate is the wrong metric, how to measure flow velocity in cm/s, the gyre principle and species-specific flow requirements.
Water Changes — Why You Change Water

What accumulates and depletes in a closed reef system, why regular water changes are the most reliable maintenance tool, and what they cannot replace.
Salinity — measurement, units and calibration

ppt, PSU and density — three units and how they convert, refractometer calibration, the ATC problem and why salinity affects every other measurement.
pH in the reef aquarium — what it is and why it fluctuates

The logarithmic scale, diel variation, safe range, indoor CO₂ as a hidden cause, and why an electrode is the only reliable measurement tool.
Alkalinity — the buffer beneath the surface

What alkalinity is, why it depletes, reference values by tank type, measurement methods and supplementation from kalkwasser to calcium reactors.
Calcium — the skeleton's building block

What corals are built from, why calcium depletes, magnesium's role in the calcium system and what happens when calcium drops too low.
Magnesium — the invisible stability mechanism

Why seawater contains so much magnesium, its role in aragonite crystallisation and calcium solubility, and how its depletion shows up in the tank.
Phosphate — the first thing a new hobbyist should measure

What happens when phosphate is absent, what happens when there is too much, the target range, measurement methods and three rules to remember.
Trace elements in the reef aquarium — why they matter

The biological role of trace elements, the most important ones, and ICP-based dosing in the reef aquarium.
Coral Groups: LPS, SPS, and Soft Corals

A beginner's guide to the three coral groups — what they are, how they differ, and the order in which to approach them.
Protein skimmer — principles, selection and use

The physics of foam fractionation, sizing principles, skimmate interpretation, CO₂ scrubber and pH connection, and the most common adjustment mistakes.
Lighting — the role of light in a reef aquarium

Why corals need light, what PAR and DLI mean in practice, and how to choose the right lighting level for different coral types.
Activated carbon — principles, selection and use

Activated carbon's adsorption principle, quality differences, reactor sizing, replacement intervals and risks — when to use it and when to leave it out.
Soft Corals — What They Are and What You Need to Know Before Your First Purchase

The basics of soft corals: biology, main groups, palytoxin warning, and what 'easiest group' really means.
Using AI to support the hobby — the basics

Where AI helps in reef keeping, what a language model does well and where it fails, and why it never replaces measurements or experience.
Anemones and clownfish — symbiosis and care

How the clownfish–anemone symbiosis works, why the bubble tip is the hobby's number-one host, and what an anemone really demands in light, flow and tank maturity.
Fish Selection and Compatibility

How to plan a fish community as a whole before the first purchase — tank size, bioload, the principles of compatibility, stocking order, the reef-safe concept and good beginner fish.
The basics of filtration

What filtration means in a reef aquarium: mechanical, biological and chemical filtration, what each does and how they work together to keep the system clean and stable.
Biological load and fish quantity

What biological load (bioload) means and why it determines how many animals an aquarium can hold. The basic concept: load is not a head count but the metabolic load the system has to process.
Live rock — the basics

What live rock is and why it is the foundation of biological filtration in a reef aquarium: bacterial surface area and the nitrogen cycle, types of rock, the life that comes with it, and handling and curing.

Practice

Concrete guides, protocols and choices.

Starting a reef tank step by step

A practical guide to assembling a new reef tank in order: placement and load-bearing, dry assembly and leak test of the equipment, substrate and rockwork, mixing and filling with saltwater, starting and tuning the equipment, and beginning the cycle — with exact figures, tolerances and troubleshooting.
The cycling process in practice — protocol, equipment and when the tank is ready

Step-by-step cycling protocol: filling, seeding, monitoring, ICP test and equipment startup.
The microbiome as the tank's foundation

What the microbiome is, what it does, how DOC and oxygen drive microbial balance — and why the hobbyist's daily choices affect it more than most realise.
Zooplankton and phytoplankton — practical addition, dosing and maintenance

Practical protocol for seeding, dosing and maintaining phytoplankton and copepods in the reef aquarium.
Culturing phytoplankton and copepods at home

A practical guide to running your own Nannochloropsis culture and Tisbe copepod culture: equipment, parameters, harvesting, combining the two cultures and avoiding crashes.
Cleanup crew — the right animals, the right time

Selecting, sizing and timing the cleanup crew: snails, hermit crabs, urchins and sea stars in the reef aquarium.
The big three in practice — measurement, target values and balance

The interdependence of alkalinity, calcium and magnesium, target values by tank type, measurement methods and signs of imbalance.
Substrate in practice — three choices and the one dangerous middle ground

DSB, SSB or bare bottom — a practical comparison of three options, cleanup crew by substrate type, and the middle ground to avoid.
Water Changes in Practice — Rhythm, Volume, and Technique

How often and how much to change water, how to prepare replacement saltwater, the mechanics of a water change, automation options, and what water changes cannot do.
Cyanobacteria in the aquarium — identification and treatment

Identification, cause hierarchy — nutrients, flow, light, DOC — and treatment protocol from chemical to antibiotic.
Dinoflagellates in the aquarium — identification and treatment

Species identification with a microscope, two treatment strategies (swimmer vs. sand dinos), UV sizing, silicate treatment, Ostreopsis safety warning and relapse risk.
Aiptasia and vermetids — identification and control

The two most common pests that hitchhike in on live rock and coral: identifying the glass anemone and the tube snail, why they are a problem, and how to control them without making things worse.
Refugium in practice — structure, macroalgae and daily management

The refugium's four biological functions, macroalgae species comparison, lighting, reverse cycle, trace element compensation, harvest schedule and comparison with Chaeto reactors.
Water flow in practice — pumps, placement and dead zones

The turnover rate myth debunked, flow's five biological functions, species-specific needs, gyre setup, dead zone diagnosis and coral behaviour as a flow indicator.
Lighting in practice — LED fixture selection, placement and photoperiod

LED fixture selection, placement, optics, acclimation and photoperiod — the variables that get your PAR value right and keep it there.
Light is not set by eye — the PAR meter in practice

What PAR and cPUR measure, why LED lighting requires measurement, species-specific reference values and the principles of light acclimatisation.
pH in practice — diagnosis, raising and management

The air test, causes of low pH in order of frequency, all raising methods compared, electrode calibration, and a monitoring schedule.
Allelopathy — chemical competition in a closed system

Allelopathy in the reef aquarium: where it comes from, how it manifests, and how to manage it with activated carbon, ozone and placement.
Mixing Saltwater Correctly

A concrete process for flawless saltwater preparation — RO/DI water as the base, salt into water, mixing time and aeration, temperature and precipitation, aging vs. fast-mixing salts, and checking parameters before use.
Brown Jelly Disease: Recognition and Treatment

A practical guide to brown jelly disease in LPS corals — what causes it, how to tell it apart from normal mucus, first aid step by step, dip options and prevention.
RTN and STN: Recognising and Treating Tissue Loss

A thorough practical guide to stony-coral tissue loss — what happens inside the coral, how to tell RTN and STN from other causes, root causes, first aid step by step, the full Witchhazel protocol and prevention.
LPS Corals in Practice: A Family-by-Family Guide

A practical guide to keeping LPS corals species and family at a time — placement, light and flow, feeding technique, choosing a healthy specimen, aggression management and introducing a coral to the tank.
Using AI to support the hobby — in practice

Practical workflows with AI: Claude's basic setup for a hobbyist, the structure of a good prompt, and concrete examples from interpreting water parameters to identifying problems.
LPS, SPS, and Soft Corals in Practice

A practical guide to parameters, placement, allelopathy, feeding, and mixed-reef technique for each coral group.
Coral Cutting and Propagation in Practice — Tools, Techniques, and Recovery

A practical guide to cutting and propagating corals: the right tools, techniques by coral group, gluing methods, plug selection, and how to manage the recovery period.
Laboratory tests in the reef aquarium — from chemical analysis to biological testing

ICP-MS, SAC254, N-DOC and microbiome DNA sequencing — what a home test cannot reach and when a laboratory is justified.
Coral dipping and quarantine protocol

Riuttareef's three-dip protocol for maricultured and wild-caught corals — Nyos Coral Dip, Reef Primer and hydrogen peroxide — plus aquacultured coral handling.
Dissolved organic carbon (DOC) — the invisible parameter that explains tank health

What DOC is, how SAC254 measures it, why refractory fractions accumulate in closed systems, and how ozonation, activated carbon and skimming affect DOC cycling.
Ozonation in the reef aquarium

Ozone chemistry, ORP control, equipment, trace element interactions with iodine and bromine, safety protocol and the connection to DOC dynamics.
Carbon dosing in practice — when, how, and when not to

When carbon dosing is justified, comparison of carbon sources, the Tropic Marin product family by PO₄ level, dosing, risks and how to prepare for them.
Calcium in practice — measurement, target values and dosing

Target values by tank type, the calcium-alkalinity relationship, measurement methods, dosing options compared and signs of imbalance.
Magnesium in practice — measurement, target values and dosing

Target values by tank type, why magnesium falls, dosing and correction, and signs of problems and impure salts.
Phosphate in practice — measurement, target values, management

Target values by tank type, N:P ratio, GFO trace element removal data, raising and lowering phosphate, and the zero-zero trap from a phosphate perspective.

Deep dive

Scientific background and mechanisms.

Euphyllia Genus: A Deep Dive

A comprehensive guide to the biology, care, diseases, and pests of the Euphyllia genus — hammer, frogspawn, and torch corals in detail.
Limewater (Kalkwasser) — chemistry and use

A deep dive into the chemistry of limewater: calcium hydroxide solubility, simultaneous Ca/ALK/pH support, the capacity ceiling, vinegar boosting, integrating trace elements, and modern safe dosing.
SPS Corals: Deep Dive

A comprehensive guide to SPS coral care — especially Acropora — for the experienced hobbyist: taxonomy, ULNS vs. moderate nutrients, N:P balance, lighting, flow, RTN/STN, pests, acclimation and tank maturity requirements.
Soft Corals in the Reef Tank

A deep dive into soft corals: biology, main groups, lighting, flow, allelopathy, nutrients, mixed reef, propagation and troubleshooting.
Zooxanthellae and the coral symbiosis

A deep dive into the relationship between a coral and its endosymbiotic algae: the biology and genera of Symbiodiniaceae, nutrient exchange and light-enhanced calcification, regulation of symbiont density, the mechanism of bleaching and the scientific debate around it — and what all of it means in the aquarium.
Coral heterotrophy and the science of feeding

A deep dive into how much heterotrophy really contributes to a coral — why it has been underestimated, what a coral actually retains from food (nitrogen and fatty acids, not carbon), how digestion works, and how fish excretions feed corals. Recent peer-reviewed research (Communications Biology 2025, Aquaculture Nutrition 2025) and what it means in the aquarium.
Coral Color and Pigments — from GFP proteins to zooxanthellae density

Why corals are colourful, how fluorescent proteins and chromoproteins work, how light and nutrients drive colour, and what bleaching reveals about the pigment system.
Cyanobacteria — Earth's oldest photosynthesiser in the reef ecosystem

Cyanobacterial evolution, nitrogen fixation, endoliths, holobiont role, toxins and allelopathy — the biological reality behind the practice article.
Iodine and Bromine in the Reef Aquarium — the halogens that rarely get measured

Iodine speciation (iodate, iodide, organic), bromine's role in skeletal construction and chromoprotein synthesis, deficiency and overdose symptoms, supplementation, and measurement.
Trace elements, macro-nutrients and micro-nutrients in the reef aquarium

A comprehensive guide to all ICP-OES element groups — macroelements, dynamic elements and the relevance line explained in practical terms.
Lighting — zooxanthellae, the Stokes shift and photoacclimation

Cell-level light physiology: zooxanthellae, chlorophyll absorption peaks, the Stokes shift, photoacclimation and photoinhibition.
Refugium — microfauna, trace element chemistry and biological balance

Copepod ecology under predation pressure, macroalgae trace element mechanisms, DOC dynamics, the refugium's role in competitive ecology and the microbial loop.
Substrate — from redox gradients to H₂S chemistry and Jaubert's plenum

Sand's redox stratification, anaerobic denitrification zones, H₂S chemistry, meiofauna and Jaubert's plenum method.
Carbon dosing — biochemistry, the microbiome and open questions

Two distinct biological mechanisms, DOC's effect on microbiome composition, biopellets and PHB, and the questions science cannot yet answer.
Dinoflagellates — ecology, toxins and biological control

Why dinos are opportunists not invaders, Shewanella bacterium's algicidal activity, Dictyota allelopathy, ovatoxin biochemistry, cysts and why the biological control system collapses in aquariums.
pH — carbonate chemistry, cellular regulation and nature's paradoxes

The carbonate system's three forms, aragonite saturation state, the vital effect, the Bourake paradox, and ocean acidification in aquarium context.
The physics of water flow — from the boundary layer to cilia

Diffusive boundary layer as a bottleneck, Shapiro 2014 ciliary paradigm, colony morphology as a flow modifier, gyre hydrodynamics and open research questions.
Allelopathy — molecular-level chemical ecology

The biochemistry of allelopathy: terpenoid structure, the cembranoid family, macroalgal isoprenoids and the mechanism of action at the coral cell level.
Iron and dinoflagellates

Why the absolute level of iron is a misleading starting point for managing dinoflagellates — the competition model, biological mechanism and practical steps.
Phosphate deep dive — biochemistry, the skeleton and open questions

Phosphate forms in water, phosphate as the cell's fundamental molecule, the one-way path into the skeleton, calcification inhibition biochemistry, particulate phosphate and Liebig vs. Redfield.
Zooplankton and phytoplankton in the reef aquarium — biological basis and ecological significance

Plankton biology, copepod fatty acids, the microbial loop and the ecological significance of heterotrophy in the reef aquarium.
Ammonium and urea as nitrogen sources

The biological advantages of ammonium and urea as nitrogen sources for corals, the scientific research base and EU-market products in spring 2026.

Reference

Concise reference articles and tables.

Dosing Methods — How to Choose the Right System for Your Reef

A comprehensive guide to the most widely used reef dosing methods in Europe: one-part, two-part, Balling variants, Triton Core7 Flex, kalkwasser, and calcium reactor — comparison, products, and practical recommendations.
Nitrate — the other half of the nutrient pair

Nitrate's role in the nitrogen cycle, reference values by tank type, managing the nutrient pair and avoiding the 0/0 trap.