Aquarium Systems is a brand that has been producing aquarium equipment since the 1970s, and their protein skimmer lineup spans from compact hang-on-back models to larger sump-compatible units. Their skimmers are sold under the Aquarium Systems name as well as through related brands, and they show up frequently in European markets and through US distributors. If you're researching an Aquarium Systems protein skimmer, you're likely looking at their SeaClone or Aqua C Remora-comparable models, or trying to understand how the brand positions relative to more well-known names like Reef Octopus or Bubble Magus.

This guide covers how protein skimmers work in general, what sets Aquarium Systems' approach apart, how to choose the right skimmer for your tank, and how to set one up correctly. I'll also compare performance characteristics so you have a realistic picture of what to expect.

How Protein Skimmers Work

A protein skimmer removes dissolved organic compounds from saltwater before they break down into ammonia, nitrite, and nitrate. It does this through a process called foam fractionation: air is mixed with saltwater in a reaction chamber, creating thousands of tiny bubbles with a large collective surface area. Dissolved organic molecules, which are naturally attracted to the air/water interface, stick to these bubbles. The bubbles rise through the reaction chamber and collect in a cup at the top as a dark, concentrated foam called skimmate.

The efficiency of this process depends on bubble size, contact time between bubbles and water, and the water volume processed per hour. Smaller bubbles have more surface area relative to their volume and collect more organics. This is why most modern skimmers use needle wheel or venturi pumps that create fine bubbles rather than simple airstones.

The skimmate collected in the cup looks like dark brown or black liquid tea in a well-tuned skimmer. Watery, light-colored skimmate means the skimmer is pulling more water than dissolved organics. Very dry, dark skimmate means the skimmer may be slightly under-powered for the bioload.

Aquarium Systems Skimmer Models

SeaClone 100 and SeaClone 150

The SeaClone series is Aquarium Systems' most recognized product line in the US market. The SeaClone 100 is rated for tanks up to 100 gallons and uses a venturi-style pump to mix air into the water column. The SeaClone 150 steps up to 150 gallons in the manufacturer's rating.

In practice, the SeaClone models have a reputation for being difficult to tune. The air intake and water level adjustments are sensitive, and the skimmer produces inconsistent skimmate (sometimes wet, sometimes nothing) while hobbyists are dialing it in. Once tuned, it works adequately for lightly stocked tanks. For heavily stocked systems or reef tanks with high nutrient loads, experienced reefers typically rate the SeaClone's performance below comparably priced options from Reef Octopus or Bubble Magus.

The SeaClone 100 fits on tanks up to 1 inch thick glass/acrylic and hangs on the back. It's a hang-on-back (HOB) design that doesn't require a sump.

Instant Ocean SeaClone

Instant Ocean (a brand under the same parent company as Aquarium Systems) markets a version of the SeaClone under their own branding. The performance characteristics are the same. If you're seeing it listed as an "Instant Ocean SeaClone," it's the same physical product in different packaging.

Performance Comparison: Aquarium Systems vs. Alternatives

For a 50 to 75 gallon reef with moderate stocking, here's how comparable skimmers compare:

Aquarium Systems SeaClone 100: Rated to 100 gallons, HOB design, around $80 to $100. Effective for lightly stocked systems. Finicky to tune. Better for FOWLR (fish-only with live rock) than aggressive reef setups.

Reef Octopus BH-100 HOB: Rated to about 100 gallons, HOB design, around $130 to $150. More consistent skimmate production, easier to tune, Sicce pump is quieter and more reliable long-term.

Bubble Magus QQ1 HOB: Rated to 53 gallons, around $80. More appropriate for 50-gallon and smaller tanks. Simpler construction but produces good skimmate once adjusted.

Aqua C Remora Pro: Rated to 75 gallons with Maxijet 1200 pump, around $200. The long-standing reliability benchmark for HOB skimmers. Expensive but rarely needs service and produces consistent results.

If you're comparing purely on price and your tank is lightly stocked, the SeaClone is in the ballpark. If you're running a reef with corals and several fish, the Reef Octopus or Aqua C Remora would serve you better at a similar or moderately higher price point.

For a complete comparison of the top-performing skimmers across different tank sizes, our guide to the best protein skimmers covers HOB and sump models side-by-side.

Setting Up and Tuning an Aquarium Systems Skimmer

The process for setting up any protein skimmer is similar, but the SeaClone has a few specific notes worth knowing.

Initial Setup

Mount the skimmer on the tank rim so the intake tube hangs into the water. The skimmer body should be outside the tank with the intake and return tubes submerged. Make sure the return tube directs water back into the tank rather than onto the glass or rim where it will drip.

Fill the skimmer body with tank water by running the pump briefly with the outlet closed, then opening it slowly. This prevents a large air bubble from getting trapped in the body, which disrupts foam production.

Break-In Period

Like most skimmers, the SeaClone produces watery, overflowing skimmate for the first 3 to 7 days as the pump and collection cup components develop the surface characteristics needed for proper foam formation. This is normal. Empty the cup daily during this period and adjust the water level so the cup doesn't overflow onto your tank rim.

Tuning the Air Intake

The SeaClone's air intake sits at the top of the pump body. A small adjustment of the air intake valve changes the bubble density inside the skimmer body. More air produces more bubbles and more aggressive foam rise. The goal is stable, moderately dense foam that rises slowly into the collection cup rather than rapidly overflowing or barely reaching the cup at all.

The water level adjustment tube controls how high the foam rises. Raising this tube lowers the effective water level inside the skimmer, which causes foam to rise higher. Lowering it raises the internal water level and reduces foam height. Getting this balance right for your specific tank's organic load takes a few days of observation and small adjustments.

Ongoing Maintenance

Clean the collection cup every 2 to 3 days. Skimmate left sitting in the cup creates a film that reduces surface tension and causes inconsistent performance. Rinse the cup with clean water and wipe it dry.

Clean the neck of the skimmer (the tube between the reaction chamber and collection cup) weekly. Organic film buildup on the neck walls reduces foam's ability to rise into the cup. A small brush (an old toothbrush works) and warm water handles this effectively.

Clean the pump impeller monthly. A clogged impeller reduces bubble production significantly. The SeaClone's pump is accessible by pulling the impeller cover off the bottom of the pump body.

For tanks where in-sump skimming is preferred, our guide to the best in-tank protein skimmer options covers models designed for display tank mounting or sump installation.

When to Replace vs. Upgrade Your Skimmer

A skimmer that's been running 3 to 5 years may have pump wear, cracked fittings, or degraded collection cup surfaces that reduce performance even with regular cleaning. Signs that your skimmer needs replacement rather than maintenance:

  • Pump running loudly or with reduced flow even after cleaning
  • Cracked or yellowed acrylic body that's difficult to clean and potentially leaching plasticizers
  • Unable to produce consistent skimmate despite correct water level and regular maintenance
  • Your bioload has outgrown the skimmer's actual capacity

Upgrading from a SeaClone to a Reef Octopus or similar quality HOB skimmer is a common path for hobbyists who started with budget equipment and want better performance as their tanks mature.

FAQ

Is the Aquarium Systems SeaClone worth buying for a beginner reef? It's an acceptable entry point if you find it discounted. At full retail price compared to alternatives, the Reef Octopus BH-100 or the Bubble Magus QQ1 deliver better value. If you already own a SeaClone, it's worth tuning and running rather than immediately replacing. If you're shopping for your first skimmer, the market has moved past the SeaClone design for value per dollar.

Can I use an Aquarium Systems skimmer in a freshwater tank? No. Protein skimmers don't function in freshwater. The foam fractionation process depends on the surface tension properties of saltwater. In freshwater, bubbles collapse before they can carry organic compounds to the collection cup. Freshwater tanks manage dissolved organics through activated carbon, regular water changes, and biological filtration.

Why does my SeaClone keep overflowing the collection cup? The most common causes are: water level inside the skimmer body is too high (lower the water adjustment tube), a new food source or additive was introduced to the tank, soap or lotion contamination from handling the skimmer with your hands, or the tank was recently disturbed (water changes, adding new rock). Give it 24 to 48 hours to re-stabilize after any tank change before adjusting the skimmer.

How do I know if my skimmer is the right size for my tank? The practical test: a properly sized skimmer on a moderately stocked tank should fill its collection cup with dark skimmate every 2 to 5 days. If the cup fills in less than a day with very wet skimmate, the skimmer is undersized. If the cup never fills or fills very slowly with almost-black, extremely dry skimmate, the skimmer is oversized for the current bioload. Oversized skimmers aren't harmful; undersized ones leave excess organics in the water.