A protein skimmer is arguably the single most important piece of equipment on a marine aquarium after the tank itself. It removes dissolved organic compounds before they break down into nitrate and phosphate, keeping your water pristine and your livestock healthy.
How Protein Skimmers Work
Skimmers work through a process called foam fractionation. A pump mixes air and water together, creating millions of tiny bubbles. Dissolved organic waste molecules are attracted to the surface of these bubbles (they're "hydrophobic" — they stick to the air-water boundary). The dirty foam rises up into a collection cup, which you empty periodically.
The result: organic waste is physically removed from your system before it can decompose. This reduces the load on your biological filtration and helps maintain low nutrient levels.
Types of Skimmers
Hang-On-Back (HOB)
Best for tanks without a sump. They clip onto the back of your tank or sit in a rear chamber. Limited by space constraints but convenient for nano and small tanks.
Good for: Tanks under 150L without a sump
In-Sump
The most common type for serious setups. Sits in your sump chamber and is generally more efficient than HOB models because they can be larger and have more contact time.
Good for: Any tank with a sump (our recommendation for most setups)
External/Recirculating
High-end skimmers that sit outside the sump with a dedicated feed pump. Maximum efficiency and easy maintenance, but expensive.
Good for: Large tanks (500L+) or heavily stocked systems
Sizing Your Skimmer
Always oversize your skimmer. A skimmer rated for your exact tank volume will be working at maximum capacity with no headroom. We recommend:
- Fish-only tank: Skimmer rated for 1.5x your total water volume
- Mixed reef: Skimmer rated for 2x your total water volume
- SPS-dominant reef: Skimmer rated for 2–3x your total water volume
For example, a 300L mixed reef should use a skimmer rated for 500–600L.
What Makes a Good Skimmer
Bubble Quality
The best skimmers produce a dense, uniform mist of tiny bubbles. Smaller bubbles = more surface area = more efficient waste removal. Look for skimmers with needle-wheel or mesh-wheel impellers.
Contact Time
Longer contact time between bubbles and water means more waste is captured. Taller skimmer bodies and recirculating designs maximise contact time.
Build Quality
A good skimmer should run for years with minimal maintenance. Look for quality pumps (Sicce, Aqua Medic, or Varios), solid acrylic construction, and easy-to-remove collection cups.
Noise Level
Some skimmers are whisper-quiet, others sound like a jet engine. If your tank is in a living space, noise matters. DC-powered pumps tend to be quieter and allow speed adjustment.
Our Recommendations by Tank Size
Under 100L (Nano)
- Tunze 9001 — compact, reliable, quiet
- Aqua Medic EVO 500 — good value
100–300L
- Reef Octopus Classic 110 — excellent performance for the price
- Tunze 9004 — proven reliability
300–600L
- Reef Octopus Regal 200 — outstanding bubble quality
- Nyos Quantum 160 — premium build, very quiet
600L+
- Reef Octopus Regal 300 — workhorse for large systems
- Royal Exclusiv Bubble King — the gold standard (if budget allows)
Maintenance Tips
- Clean the collection cup weekly — a dirty cup reduces efficiency
- Soak the pump in citric acid or vinegar every 2–3 months
- Check the airline — blocked airlines reduce bubble production
- Break-in period — new skimmers take 1–2 weeks to start skimming effectively. Be patient.
- Adjust the water level — most skimmers have a water level adjustment. Start with a wetter skim and gradually raise it for drier, more concentrated skimmate.
Need Help Choosing?
Bring your tank dimensions and stocking plans into Eastwood Aquarium. We stock a range of skimmers and can help you find the right one for your setup and budget. We also carry replacement parts and pumps for most major brands.