Saltwater Aquarium Filter Beginner Guide: AIO to Sump
Filtration on a reef tank is less about stages of mechanical media and more about the whole water-processing system — skimmer, refugium, flow, display biology. Freshwater keepers stepping across for the first time often treat a canister as enough and end up cycling forever. This saltwater aquarium filter beginner guide from Gensou Aquascaping at 5 Everton Park breaks down the four filtration architectures you will see across Singapore reef builds, their real SGD costs, and which one fits a nano HDB tank versus a landed-house mixed reef.
Why Saltwater Filtration Differs
A freshwater canister stacked with ceramic media handles ammonia and nitrate beautifully, because freshwater fish tolerate some nitrate and bacteria colonise sponges happily. Reef corals do not. Nitrate above 10 ppm kills colour in SPS; phosphate above 0.05 ppm feeds nuisance algae. Reef filtration strips dissolved organics before they become nitrate and phosphate — which is the skimmer’s job, not a cartridge’s. The architecture you choose determines whether a skimmer is even possible.
All-in-One (AIO) Nano Tanks
AIO tanks like the Waterbox Cube 20, Red Sea Max Nano and Innovative Marine Nuvo hide a rear chamber for media and a small skimmer. SGD 450-900 buys a complete 40-75 litre system with pump, light and overflow. Beginner-friendly because there is nothing to plumb. Limitations: the rear chamber fits only a compact internal skimmer (Bubble Magus QQ1 at SGD 120), and refugium space is cramped. Ideal for first-year reefers wanting a clean look without drilling cabinets.
Hang-On-Back (HOB) Filters
Aquaclear 70 or similar HOB units around SGD 80-120 work for FOWLR (fish only with live rock) and softie tanks where ultra-low nutrient is not the goal. Run filter floss for mechanical and a Marine Pure cube for biological. Add a separate HOB skimmer (CPR SR4 at SGD 220) and you have a respectable beginner reef filter stack. Not adequate for SPS or LPS-dominant mixed reefs because dissolved organic processing is limited.
Canister Filters on Reef Tanks
Canisters like Eheim 2217 (SGD 280) or Fluval 407 (SGD 320) can run reef duty if you treat them as nutrient export rather than storage. Load filter floss and activated carbon only, service weekly, and never leave old bio-media to accumulate detritus. Skip the ceramic cylinders — they become nitrate factories. Pair with an external skimmer hung off the sump or standalone. Canisters are the middle-ground pick for 200-400 litre tanks without sump space.
Sump Filtration — The Reef Standard
A sump is a second tank under the display, fed by a drilled overflow, housing the skimmer, refugium, heater, ATO reservoir and return pump. Trigger Systems Ruby 30 sumps run SGD 380-550, custom acrylic sumps built by local shops start SGD 250. The investment unlocks proper reef-grade skimming (Reef Octopus Regal 150 at SGD 450) and refugium space for chaeto. Mandatory for mixed reefs above 200 litres targeting SPS. Plumbing cost adds SGD 150-200 for Bean Animal overflows, unions and PVC.
Mechanical Filtration — Floss and Socks
Filter socks (100-200 micron, SGD 25 per 4-pack) sit in the sump inlet catching detritus before it breaks down. Swap every 3-4 days in SG’s warm conditions or they become nitrate sources. Filter roll upgrade systems (Clarisea SK-3000 at SGD 420) automate this for busy keepers. Filter floss in AIO chambers does the same job — keep it fresh, swap weekly minimum.
Biological Filtration on Live Rock
Your live rock IS the biological filter on a reef. Dry rock cycles in 6-8 weeks with bottled bacteria; live rock from C328 Clementi (SGD 18-25 per kg) is pre-colonised and shortcuts the cycle. Budget 1 kg of rock per 5 litres of display volume. Skip the ceramic rings — they sit in low-flow dead zones in canisters and clog. All reef biological load lives on the rock and sand surface in the display, not in an external media stack.
Flow and Filtration Work Together
A filter only processes water that reaches it. Reef flow targets 20-40 times tank volume per hour in total — a 200 litre display needs 4,000-8,000 LPH of combined return pump and powerhead output. Jebao MOW-9 powerheads at SGD 120 or MP10 replicas at SGD 150 deliver the turnover. Dead spots breed cyano and dinoflagellates regardless of how good your skimmer is.
SG Climate Considerations
Sumps dissipate more heat than sealed canisters because of surface evaporation, which helps offset skimmer and return pump heat in our 30°C ambient. That same evaporation needs auto top-off (Tunze Osmolator SGD 280) to prevent salinity creep — non-negotiable on a sump build. AIO tanks need manual daily top-off or a cheap reservoir float valve at SGD 45. Factor this into your filter architecture choice from day one.
Budgeting Your First Reef Filter Stack
Nano AIO route: Waterbox 20 SGD 600, Bubble Magus QQ1 skimmer SGD 120, Marine Pure SGD 30, float-valve ATO SGD 45. Total SGD 795. Mid-size sump route: 60 cm display SGD 400, 40 cm sump SGD 280, overflow plumbing SGD 180, Reef Octopus Classic 110 skimmer SGD 320, return pump SGD 140, ATO SGD 280. Total SGD 1,600. Skimping on the skimmer in either path is the single most common beginner mistake we see in SG client tanks.
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