Everything you need to know about keeping a successful saltwater aquarium, from your first reef tank through to quarantine, water chemistry, and choosing healthy livestock.
Coral Glossary
Search & filter 46 corals
Fish Glossary
Care sheets by species
Invert Glossary
Coming SoonPest & Parasite ID
Identify & treat
Calculators
Salinity, dosing & stocking
Quarantine Guide
Protocols & timelines
Disease Guide
Identification & treatment
All Blogs & Guides
Browse every article
Acclimation Guide
Drip acclimation & settling in
Coral Dipping Guide
Treat new corals before adding
Coral Colour & Lighting
Why your coral looks different at home
Marine Algae Guide
ID, causes & clean-up crew
Reef Tank Problem Solver
Something not quite right in the tank? Pick the issue below that matches what you're seeing and we'll walk you through why it happens and what to reach for to fix it. For anything that doesn't fit neatly into one of these, our team is always happy to help you troubleshoot.
Algae IssuesGreen film, hair algae or cyanobacteria taking over your glass and rockwork. Solutions
Nuisance algae is almost always a nutrient problem – excess phosphate and nitrate from feeding, decor or top-up water giving algae more fuel than your corals can use. Test first, then combine a strong clean-up crew with chemical filtration to bring nutrients back down. For full identification and species-specific fixes, see our Marine Algae Guide.
Aiptasia & Reef PestsAiptasia, flatworms or other hitchhikers spreading through the rockwork. Solutions
Pests hitchhike in on new corals and rock, then spread quickly once established, stinging and out-competing your corals. Dip every new coral before it goes in the display, and bring in a dedicated predator to knock back Aiptasia already in the tank. See our Marine Pest & Parasite ID Guide and Coral Dipping Guide for identification and step-by-step treatment.
Coral Not GrowingPolyps look healthy but frags and colonies just aren't putting on size. Solutions
Slow growth usually comes down to light, flow, alkalinity or a shortfall in trace elements – corals simply can't build skeleton without stable building blocks and something to feed on. Start by testing alkalinity and calcium, then add target feeding and trace elements to fill the gaps. Our Reef Tank Parameters Explained article covers how each parameter affects growth.
Corals Losing ColourOnce-vibrant corals turning pale, brown, or washed out. Solutions
Pale or browning corals are usually reacting to lighting, nutrient swings, or unstable water chemistry rather than one single cause. Confirm your parameters are stable first, then look at feeding and lighting before making changes. Read Why Your Coral Might Look Different at Home before assuming it's colour loss and not just your lighting or camera.
Fish Not EatingA fish that's gone off its food, hiding, or looking listless. Solutions
A fish off its food may simply be stressed or settling in after transport, or it could be an early sign of parasites. Rule out water quality first, offer a variety of foods it can't resist, and watch closely for other symptoms. If anything else looks off, check our Marine Fish Diseases Guide, and see the Acclimation Guide for settling in new arrivals properly.
Water Quality ProblemsUnstable parameters, cloudy water, or livestock generally struggling. Solutions
Water quality problems stress everything in the tank at once, so test first, correct the cause, then stabilise before adding anything new. A reliable auto top-off keeps salinity steady between water changes, and chemical filtration keeps organics and odour under control. Start with our Aquarium Nitrogen Cycle – Saltwater guide if you're not sure where to begin.
Getting Started
Beginner's Roadmap
Setting up your first reef tank
Best Beginner Fish
And which ones to avoid
Nitrogen Cycle
Cycling a new saltwater tank
Reef Tank Parameters
Salinity, alkalinity, calcium & more
Coral Care Guides
In-depth care guides for the corals we stock, each covering water parameters, lighting, flow, feeding, placement and troubleshooting. Browse the full Coral Glossary to search and filter by type, difficulty, lighting and flow, or jump straight into an individual care guide.
New to coral photos and colour? Start with Why Your Coral Might Look Different at Home: A Guide to Coral Photography & Lighting before browsing individual species guides.
Browse the Coral GlossaryBuying Marine Livestock
Start Here
Buying livestock online
Pre-Purchase Checklist
What to check before you buy
How We Pack
Fish, corals & plants
Arrival Guarantee
Live fish arrival policy
Airport Pickup
Live animal freight locations
Shop Marine Essentials
Tanks & Stands
Aquariums, tanks & stands
Aquarium Salt
Shop marine salt mixes
Test Kits
Test kits & monitoring
Filtration
Shop filtration
Medication
Fish medication & supplements
Water Treatments
Treatments & additives
If you have a question, our team is always happy to help.