Practical guide8 min
Coral placement, flow and aggression planning
Place coral for its future colony size, light, flow and defensive reach—not the frag plug today.
coralflowaggression
AquaNexus knowledge library
Marine systems
Original practical guides connected to the Aquatic Life Database.
19 guidesOriginal AquaNexus writingReviewed 2026-07-20
Practical guide8 min
Feeding specialist marine invertebrates
Confirm the actual food source before buying starfish, clams, sponges, tunicates or sea cucumbers.
marine invertebratesfeedingspecialist
Practical guide8 min
What a mature marine aquarium actually means
Separate calendar age from biological capacity, stability and proven feeding resources.
marinematurityreef
What is the ugly stage in a new reef aquarium?
Understand common early blooms without treating every film as an emergency.
Read guide →Marine & reefWhy does salinity rise when aquarium water evaporates?
Replace evaporated freshwater without adding more salt.
Read guide →Marine & reefWhy is alkalinity important in a reef aquarium?
Keep carbonate availability stable for calcification and pH buffering.
Read guide →Marine & reefHow do calcium and magnesium work in a reef tank?
Understand the relationship among major ions used by corals and coralline algae.
Read guide →Marine & reefDo I need a protein skimmer on a saltwater aquarium?
Decide from nutrient export, gas exchange, stocking and maintenance style.
Read guide →Marine & reefWhat nitrate and phosphate levels are best for a reef tank?
Manage nutrients as a balanced range rather than chasing absolute zero.
Read guide →Marine & reefHow often should a reef aquarium have water changes?
Set a schedule from nutrient export, trace-element demand and testing.
Read guide →Practical guide10 min
How do I fishless-cycle a saltwater aquarium?
Establish and verify biological filtration with a controlled ammonia source before adding fish, then stock slowly as the system matures.
marine cyclefishlessammonia
Practical guide9 min
How should I mix saltwater for an aquarium?
Measure purified water, add a known marine salt mix with circulation, allow it to dissolve and stabilise, then confirm salinity and temperature before use.
mixing saltwatersalinitymarine salt
Practical guide10 min
What should I do if marine salinity is too high or too low?
Confirm the reading with a calibrated instrument, then correct salinity gradually using fresh water or matched saltwater while protecting temperature and oxygen.
salinityspecific gravityosmotic stress
Practical guide10 min
How do I respond to ammonia in a marine aquarium?
Increase aeration, stop feeding, remove decay and dilute with matched saltwater while protecting the biological filter.
marine ammoniareef emergencywater change
Practical guide10 min
Why is pH low in my reef aquarium?
Low reef pH often reflects excess carbon dioxide or low alkalinity; confirm measurement and solve gas exchange and buffering causes separately.
reef pHalkalinitycarbon dioxide
Practical guide10 min
Why is my coral not opening?
Check water stability, light, flow, pests and nearby aggression; closed polyps are a symptom, not a diagnosis.
coral closedpolyp extensionreef stability
Practical guide10 min
What should I do if aquarium coral is bleaching?
Bleaching is loss of symbiotic algae or pigment and requires immediate stabilisation of temperature, light, water chemistry and other stressors.
coral bleachingheat stresslighting
Practical guide11 min
Are the brown or red mats dinoflagellates, cyanobacteria or diatoms?
Identify texture, bubbles, timing and microscopy before choosing a treatment; these groups respond to different system conditions.
dinoflagellatescyanobacteriadiatoms
Practical guide11 min
How do I protect a reef aquarium during a power outage?
Prioritise oxygen and circulation, then temperature and filtration; do not feed until stable power and water quality return.
reef outagebackup aerationtemperature