Brand new to reefing?

RO/DI means reverse-osmosis deionised water. Mix it with marine aquarium salt according to the salt’s instructions and verify salinity before use.

Evaporation leaves salt behind. Replace evaporation with freshwater, not saltwater. An automatic top-up can help maintain consistency.

A sump is a separate tank connected beneath or beside the display, providing space for equipment and filtration. It is useful, but not essential for every setup.

Start with a manageable aquarium and a realistic livestock list. A larger water volume usually changes more slowly, but costs more to light, heat and maintain. Small tanks can work well, provided you understand that evaporation, feeding and dosing have a greater effect on less water.

Choose a level, load-bearing position away from direct sun and strong temperature changes. Leave access to pumps, filters and pipework. Plan safe electrical connections, drip loops and somewhere to mix and store water before filling the tank.

Biological filtration provides surfaces where waste-processing microbes live. Mechanical filtration catches suspended particles, which you must physically remove. A protein skimmer removes some organic material before it breaks down. None of these replaces sensible stocking or regular cleaning.

Flow should circulate the whole aquarium without constantly blasting tissue off a coral or leaving waste in dead spots. Lighting must suit the species and placement. Begin conservatively and increase light gradually when needed; a brighter-looking aquarium does not automatically have better coral lighting.

Buy marine-compatible tests and enough supplies to repeat them. At startup you need ammonia, nitrite and nitrate tests, plus reliable temperature and salinity measurement. Add alkalinity and phosphate testing before introducing corals, with calcium and magnesium tests for growing stony corals. You do not need to buy every trace-element test to start.

Evaporation removes water while leaving most salts behind, so salinity rises. Top up with RO/DI freshwater. An automatic top-up replaces small amounts frequently, but you still need to check its reservoir, sensor and operation.

A water change removes saltwater and replaces it with newly mixed saltwater. Mix in a separate container, follow the salt instructions, allow it to dissolve fully, and verify temperature and salinity before use.

Mark a normal water level and estimate the actual system water volume after rock, sand and equipment displace water. Supplement instructions use water volume, not the tank’s advertised capacity. Recheck salinity after maintenance; never correct a large discrepancy by adding dry salt around animals.

Follow your cycling product’s instructions, including its measured ammonia source. Confirm the aquarium can process the prescribed addition, returning ammonia and nitrite to undetectable levels in the specified period—commonly 24 hours.

Only perform an ammonia challenge before animals are present. Check temperature, salinity, and nitrate before stocking.

Microbial communities keep changing after the initial cycle. Rock, stocking, feeding, and maintenance affect development; there is no universal date when every aquarium becomes mature.

1. Set up mixed saltwater at the intended salinity and temperature. Run circulation and the biological filter. Follow the bacteria product’s instructions for equipment such as UV or a skimmer; instructions differ between products.

2. Add the prescribed bacteria and measured aquarium ammonia source. Do not use a fish as an ammonia source, and do not keep adding ammonia simply because the first reading has fallen. Excessive additions can stall progress.

3. Test ammonia, nitrite and nitrate according to the cycling schedule, often every two or three days while tracking progress. Near the final processing check, test at the prescribed interval. Log the starting dose, date, time and results.

4. Ammonia falling and nitrite appearing show one part of the process working. Nitrite subsequently falling can show the next part establishing. Nitrate is useful evidence of progress, but nitrate alone, or zero ammonia without any known input, does not demonstrate waste-processing capacity.

5. Before any animals are present, confirm the aquarium handles the instructed ammonia challenge within the specified period, commonly 24 hours. Do not repeat ammonia challenges once livestock has been added. Complete any advised water change, then check temperature, salinity and nitrate before the first small addition.

6. After introducing livestock, feed appropriately and watch for ammonia if there is concern about waste processing. Increase stocking in small steps. The bacteria need to support the load you actually add; passing a cycle test does not mean the aquarium can immediately support its eventual full stock.

The initial cycle establishes basic nitrogen-waste processing. A mature reef also develops communities on rock, sand and other surfaces, along with more predictable feeding, nutrient export and element consumption. Your habits and equipment reliability develop alongside the biology.

Allow roughly six to twelve months for a new reef to develop as a conservative planning guide. There is no household test that certifies bacterial maturity, and no calendar date guarantees success. Rock choice, stocking, feeding, disturbances and husbandry all affect the journey.

Look for several weeks of repeatable water results, animals feeding and behaving normally, corals maintaining tissue and showing growth, and a maintenance routine that holds conditions steady. If you keep having to make emergency corrections, pause the next stocking step.

Follow sample volumes, mixing and waiting times exactly. Keep test equipment clean, check reagent expiry dates, and calibrate instruments as instructed. Fingerprints and bubbles can affect digital colour tests.

Test at consistent times. Log doses and water changes. Repeat an unexpected result before a large correction; small differences may fall within the test’s uncertainty.

When establishing or adjusting dosing, daily alkalinity checks at a consistent time help reveal consumption. Occasional checks elsewhere in the dosing schedule can expose swings. Tailor ongoing testing to demand and the rate of change.

1. Read the instructions for your exact kit before starting. Use a marine test with a range and resolution suitable for the measurement. Check reagent expiry dates and storage conditions. Different kits may require different sample volumes, mixing and waiting times.

2. Take a representative sample away from a dosing outlet, food cloud or freshly added saltwater. Use the specified volume, reading the meniscus as instructed. Rinse and clean equipment using the kit guidance; detergent residue can contaminate a sample.

3. Add reagents in the prescribed order and amounts. Hold drop bottles as instructed, use the correct syringe reading, and keep the designed air gap if the instructions require one. Start a timer rather than estimating the waiting period.

4. For a colour test, compare in neutral white light. For a titration, mix between additions and use the stated endpoint rather than stopping at the first temporary colour flash. For a digital checker, clean the outside of the cuvette, remove bubbles and follow its blanking and timing steps.

5. Record the result with its units: dKH, ppm or mg/L as appropriate. Some meters report phosphorus in ppb rather than phosphate in ppm; these are not interchangeable. Use the manufacturer’s conversion when necessary.

6. Recheck an unexpected result with a fresh sample. Review technique, reagents, calibration and recent maintenance before changing the water. A digital display has measurement uncertainty too. If uncertainty remains, compare with a reference solution or another reliable test.

Why: temperature affects metabolism, oxygen availability and the conditions your animals experience. Sudden or sustained departures from a suitable range can stress the whole aquarium.

How: use a reliable aquarium thermometer or probe, positioned where it measures circulating water. Compare occasionally with a separate thermometer. A heater’s dial setting is not proof of the actual tank temperature.

What to do: look for a repeatable daily pattern and check heater operation and room conditions. Investigate a rising or falling trend early. Correct gradually where animals are stable, while responding promptly to an equipment failure.

Why: marine animals need suitable salt concentration. Salinity changes also shift the apparent concentration of calcium, magnesium and other dissolved constituents, so check it before treating several chemistry results as separate problems.

How: use a marine refractometer or suitable salinity meter. Calibrate with the standard and method specified for the instrument, allow temperature equilibration, and keep the prism or probe clean. Record salinity in a consistent unit rather than mixing salinity and specific-gravity readings.

What to do: investigate evaporation, top-up behaviour, leaks and replacement water first. Test freshly mixed water before it enters the tank. Make measured corrections rather than repeatedly adjusting salt concentration by eye.

Why: ammonia is released by waste and decay and can harm animals. Cycling converts it through nitrite to nitrate. Nitrite is useful for following nitrification during startup; its toxicity in seawater differs from freshwater, and it should not be treated as equally dangerous to ammonia.

How: use marine-compatible tests and follow the full timing instructions. Some ammonia tests measure total ammonia rather than the free-ammonia fraction; interpret the result using the kit guidance. Nitrite can interfere with some nitrate methods during cycling, so check the instructions before trusting a high nitrate result.

What to do: follow the fishless-cycle verification sequence above. In a stocked tank, confirmed ammonia alongside distressed animals needs prompt investigation of deaths, overfeeding and filtration disruption. Support oxygenation, stop unnecessary feeding temporarily, and consider a matched water change while finding the cause. Never add ammonia to test a stocked aquarium.

Why: alkalinity measures acid-neutralising capacity. Carbonate and bicarbonate also supply part of the material stony corals use to build skeletons. Growing LPS, SPS and coralline algae can draw it down daily, making it one of the most useful early indicators of changing demand.

How: use a marine alkalinity titration or checker and record dKH consistently. Test at the same point in your dosing schedule. Follow exact volumes and mixing instructions; occasional additional checks before and after doses help reveal swings a single daily reading misses.

What to do: a repeated fall may mean demand exceeds replacement. A rise may mean you are adding more than the reef uses, or new saltwater has a different KH. Verify salinity and the dosing equipment before altering the dose. Choose a suitable baseline for your livestock and salt, then hold it steadily rather than chasing another keeper’s number.

Why: stony corals and other calcifying organisms use calcium with carbonate to build calcium-carbonate structures. Growing reefs can use more than water changes replace. Soft-coral reefs often have much lower demand, but coralline algae still contributes.

How: use a marine calcium kit, follow sample preparation and the stated endpoint, and record ppm or mg/L. Compare over several days rather than expecting a small daily change to be clearly visible within the kit’s precision.

What to do: confirm a persistent trend and check salinity before supplementing. Do not add calcium because alkalinity has fallen without first testing calcium; products have different strengths and may supply more than one component.

Why: magnesium helps maintain seawater chemistry and discourages unwanted calcium-carbonate precipitation. It usually changes more slowly than alkalinity, so it generally does not need the same daily testing routine.

How: use a marine magnesium kit and follow every stage carefully. Multi-stage titration tests can be sensitive to sample volume, mixing and endpoint interpretation. Record the result alongside salinity and recent water changes.

What to do: repeat a surprising result before making a large addition. Review the salt mix and salinity first. Confirmed correction should follow the supplement instructions; magnesium is not an automatic cure for every alkalinity problem.

Why: nitrogen and phosphorus are needed by living organisms, including the photosynthetic partners within many corals. Persistent accumulation can encourage nuisance growth, but aggressive removal can leave too little available. The aim is a suitable, reasonably steady supply.

How: use nitrate and phosphate methods that can resolve the levels relevant to your reef. Follow mixing and reaction times precisely. Read whether the instrument reports phosphate or phosphorus, and whether the unit is ppm or ppb. An undetectable result means below the method’s detection capability, not proof that the tank contains none.

What to do: compare several results with feeding, livestock and nutrient export. Algae can take nutrients from the water and make a low test reading misleading. Diagnose the growth and the trend before dosing more nutrients or adding extra removal media.

Why: pH describes acidity or alkalinity, while KH describes acid-neutralising capacity. They are related but not the same measurement. Carbon dioxide, gas exchange and photosynthesis influence pH through the day.

How: use a suitable marine pH test or calibrated probe. Calibrate and store probes as instructed. Compare readings at the same time, and take morning and evening measurements initially to understand the normal daily pattern.

What to do: verify an unexpected value before acting. Review alkalinity and gas exchange, including room ventilation. Do not keep adding a buffer purely to chase pH; many buffers also raise alkalinity. A regular modest day/night swing does not mean the reef needs constant correction.

Record date, time, parameter, result and unit. Add the amount and time of any dose, water-change volume, feeding changes, new livestock, media replacements and observations of the animals. A notebook or simple spreadsheet is enough.

Example: “Monday 19:00 — KH 8.2 dKH, before dosing. Tuesday 19:00 — KH 8.0 dKH, no water change or supplement.” That suggests a fall of 0.2 dKH over the day, but confirm the pattern over several readings before choosing a maintenance dose.

A graph makes repeated rises, falls and dosing peaks easier to see. One matching pair of Sunday readings cannot tell you whether KH stayed steady or swung between tests. Regular measurements turn a guess into a trend.

Stony corals and coralline algae consume calcium and alkalinity as they build skeletons. Soft-coral systems generally have lower demand, but still need suitable chemistry.

Supplement only when testing shows your maintenance no longer keeps up. Base the total amount on measured consumption; a dosing pump delivers what you programme, not what the reef automatically needs.

Natural daily variation, especially pH, is normal. Do not chase every small movement or dose food simply to flatten a graph.

Begin with a suitable baseline and record alkalinity at consistent times for several days. Record all additions and water changes so a change in KH is not incorrectly attributed entirely to coral uptake. Consumption includes other calcifying organisms and can also include unwanted precipitation.

For a simple example, a repeatable net fall from 8.2 to 8.0 dKH in 24 hours suggests a replacement requirement of about 0.2 dKH per day under those conditions. Use the supplement’s instructions and your actual water volume to calculate the amount. Do not copy the millilitres from a different aquarium.

Correcting an existing deficit and replacing daily demand are separate jobs. A one-off correction is not automatically the daily dose. Follow product limits for corrections, make small changes and retest; do not allow levels to drop excessively just to measure consumption.

Once the total requirement is understood, smaller, more frequent additions can reduce the gap between the peak after dosing and the trough before the next dose. A dosing pump can help, but it must be calibrated and checked. Its tubing, reservoir and programming can fail.

Retest closely after changing a dose. If KH continues falling, investigate the trend before increasing again. If it rises, the dose may exceed demand. Keep calcium and magnesium in view, and separate incompatible supplements according to their instructions.

As corals grow, demand often rises. If growth slows, animals are removed or the aquarium is disturbed, demand may fall. Last month’s dose is not a permanent setting. Testing closes the loop between what you add and what the aquarium actually needs.

GFO—granular ferric oxide—and other phosphate-removing media can lower phosphate. Follow product instructions, start conservatively, and test closely after changes. Avoid stripping phosphate rapidly.

For a confirmed shortage, reef-labelled nitrate or phosphate supplements provide dosing instructions. Check feeding and removal first, then make measured additions and retest. Do not copy another tank’s dose.

Start with a repeatable baseline for both nitrate and phosphate. Test at consistent times and write down changes. A single higher reading may reflect testing uncertainty or recent feeding; a sustained rise across several tests is more useful evidence.

If nutrients keep rising, review feeding quantity, stock load and waste accumulating in filters or low-flow areas. Clean trapped waste, maintain the skimmer where fitted, and use a sensible water-change routine. Change one part of export at a time where practical, then test the response.

If phosphate remains too high for your intended reef, GFO means granular ferric oxide: an iron-based phosphate-removing medium. Other products use different materials and have different capacities. Choose the amount and placement from the product instructions, start conservatively and monitor the fall closely. Replacing exhausted media with fresh media can sharply increase removal.

If nitrate or phosphate repeatedly reads undetectable, first check the method’s low-range capability. Review whether media, a refugium or other nutrient export is too aggressive. Avoid starving fish to achieve a low number; normal appropriate feeding is part of the nutrient supply.

For a confirmed need, use a reef-labelled nitrate supplement or phosphate supplement with a stated concentration and aquarium dosing instructions. Such products may use nitrate salts or phosphate salts; formulation varies. Use the labelled calculation, make small measured additions and retest before repeating.

Nitrate and phosphate may need different adjustments. Do not dose both automatically because one is low. Carbon-based nutrient-reduction products are different from nitrate or phosphate supplements and require their own instructions, suitable equipment and close monitoring.

Soft corals generally lack a rigid stony skeleton. LPS and SPS are hobby groupings for large-polyp and small-polyp stony corals. Each includes species with different demands.

Plan adult size and compatibility. Add gradually and monitor the response. Quarantine new arrivals where possible and use a species-appropriate acclimation method.

White spot and velvet require parasites to be introduced; overstocking does not create them. Quarantine and biosecurity reduce introduction risk, while gradual stocking helps manage waste load and stress.

Choose cleanup animals for the food available. A large group of grazers may starve in a newly cycled, clean aquarium.

Progress when: the initial cycle is verified, temperature and salinity are consistent, and nitrate is suitable for the intended animals. You have a compatible livestock plan and a quarantine approach before purchase.

Start with a small addition that the aquarium can support, then wait while you observe feeding, behaviour and nutrient trends. There is no universal safe number of fish: adult size, species, filtration and water volume matter.

Choose a modest cleanup crew for the food actually present. Snails, hermit crabs and shrimp have different diets and compatibility issues; “cleanup crew” does not mean they all survive on algae or remove the need to clean. Provide suitable food where natural grazing is insufficient.

Pause if animals stop feeding, breathe unusually fast, lose condition or show disease signs. Do not solve an unsettled first stocking by buying more animals. Fish parasites such as white spot or velvet must be introduced; stocking too quickly does not create them, but it can add waste load, stress and more introduction opportunities.

Around a month after a confirmed cycle can be a reasonable point to consider suitable soft corals, if the system is behaving consistently. This is Christian’s conservative guide, not a requirement or a guarantee.

Progress when: temperature and salinity are repeatable, nitrate and phosphate are understood, suitable reef lighting and flow are available, and current livestock is healthy. Know your alkalinity baseline even where demand is low.

Start with one or a few suitable corals. Acclimate to light gradually, allow room for growth and assess compatibility. Soft corals generally impose less calcium and alkalinity demand than stony corals, but “soft” does not mean every species is equally easy.

Look for retained tissue, normal extension for that species and sustained growth. Temporary closing after a move is different from continuing deterioration. Pause further additions while you investigate a coral that repeatedly declines.

Around months three to four, consider suitable beginner LPS if the earlier stage is settled. LPS means large-polyp stony corals, a broad hobby grouping rather than a single care requirement.

Progress when: you can demonstrate stable salinity and temperature, a suitable nutrient trend, and repeatable alkalinity, calcium and magnesium results. Confirm species-specific light, flow, feeding and space requirements before buying.

LPS build a stony skeleton, so begin tracking consumption rather than assuming water changes will always be enough. Check alkalinity more frequently after additions and as growth increases. Supplement only when testing shows that replacement is needed.

Allow space for expansion and stinging tentacles. Start with a small number and judge progress by healthy tissue and growth. If chemistry needs frequent corrections or corals are losing tissue, hold this stage instead of moving on to SPS.

Six months onwards is a cautious point to consider suitable SPS, provided the aquarium can support them. More demanding corals, including many Acropora, often perform better in a more established system. Waiting through the first year can give both the reef and the keeper time to develop.

Progress when: you have several weeks of meaningful records showing controlled alkalinity demand, steady salinity and temperature, understood nutrient trends, and healthy existing corals. Suitable light and distributed flow are essential; a tank’s age cannot compensate for missing fundamentals.

SPS means small-polyp stony corals. Different species and even individual colonies can respond differently. Start with a manageable, suitable coral, then monitor growth and chemistry before expanding the collection.

Keeping a coral alive is different from helping it thrive. Look for sustained growth, healthy tissue and colour appropriate to the coral over time. Do not treat a twelve-month birthday as proof of bacterial maturity, and do not force progress through an unresolved outbreak or unstable dosing routine.

Growth smothering corals or appearing alongside distressed animals needs prompt investigation. Different algae and microbes need different responses; a brown film alone does not identify the cause.

Do not assume every outbreak will disappear without attention, or that having no early bloom proves the reef is mature.

New tanks commonly develop films and nuisance growth as surfaces are colonised and nutrient inputs change. Some develop early brown dusting, later green growth or episodes of slime. The order and timing vary; a quiet first few months does not guarantee that no outbreak will appear later.

Identify before treating. Brown dust, stringy mats and bubbles are clues, not a confirmed diagnosis. Diatoms, cyanobacteria and dinoflagellates can look similar at a glance, and some require microscopy to identify confidently.

Check the basics: salinity, temperature, nutrient trends, feeding, light schedule, trapped detritus and flow. Remove accessible nuisance growth and maintain equipment. Keep changes measured so you can see which intervention helps.

Avoid rapidly driving nitrate and phosphate to undetectable levels merely because algae is visible. Growth may already be taking nutrients out of the water, and excessive removal can create a different problem. Do not repeatedly restart the aquarium or sterilise biological surfaces as routine cosmetic maintenance.

If growth smothers coral, livestock struggles or the outbreak keeps worsening, investigate promptly. Patience means resisting unnecessary changes while keeping up good husbandry; it does not mean ignoring declining animals.

Prepare replacement saltwater according to its instructions, verify salinity, and match temperature closely before use. Never add dry salt directly around livestock.

Avoid overfeeding, adding too many animals together, making several corrections at once, and treating before identifying the problem. Change one thing at a time where practical, then observe the response.

Choose a repeatable water-change routine suitable for your stocking and nutrient trends. A modest regular change is often a practical starting approach. Its value comes from replacing some water and dissolved constituents and allowing removal of waste, not from a magic percentage.

Mix replacement water separately using RO/DI and marine salt. Follow the mixing instructions, check temperature and salinity, and know how its alkalinity compares with the aquarium. A large change with very different KH can itself create a swing.

Remove measured saltwater and accessible waste, replace with prepared saltwater, then check equipment and water level. Account for automatic top-up while the level is temporarily low so it does not replace removed saltwater with freshwater.

Log the change and review its effect on results. Water changes can meet modest element demand, but a growing stony-coral reef may consume more than they replace. Test to establish that rather than adding supplements automatically.

Every day: observe animals before focusing on numbers. Check temperature, pumps, heater, top-up and dosing reservoirs. Feed appropriately and remove anything dead promptly. A normal-looking controller screen does not confirm water is flowing or a dose is reaching the tank.

Every week: review recorded trends, complete the planned tests, remove captured waste from mechanical filters and maintain the skimmer. Clean glass and accessible detritus without stripping all biological surfaces. Match cleaning frequency to how quickly waste collects.

Periodically: clean pumps, inspect tubing and connections, check dosing-pump delivery, calibrate salinity and pH instruments as instructed, and inspect test reagent dates. Check equipment after cleaning before assuming it has restarted correctly.

After a change: tighten the relevant testing routine. New corals can increase KH demand; new removal media can decrease phosphate; a feeding change can alter both nitrate and phosphate. Record the intervention and allow a sensible observation period before stacking another correction.

Testing only when something looks wrong: set a regular routine so you can recognise the tank’s normal pattern and catch changes early.

Dosing from one surprising number: repeat the test, check technique and recent events, then make a measured correction if the problem is confirmed.

Buying more animals because the calendar says you can: use the readiness checks and the response of existing livestock. Time supports development; it does not certify readiness.

Making several changes together: where practical, change one thing, log it and check the result. Otherwise you may not know which change helped or made matters worse.

Assuming automation means the job is done: check sensors, reservoirs and actual delivery. Equipment makes consistency easier only when it is maintained and verified.

Pause new livestock if existing animals are deteriorating, disease is suspected, the aquarium is not handling its current load, or salinity, temperature and chemistry keep requiring rescue corrections.

Return to the basics, verify unexpected tests, inspect equipment and identify the cause. Establish a repeatable routine and watch existing animals recover before taking the next step. A short pause costs less than repeatedly replacing animals.

You are ready to progress when you understand the trend, can maintain suitable conditions and can explain how you will meet the next animal’s needs. The aim is a reef that grows steadily with your confidence.