Tunze DOC Skimmer 9004 DC

The Tunze DOC Skimmer delivers efficient, low-power protein skimming sized to match your saltwater aquarium’s volume.

• Hang In Skimmer. Comes with Magnet for ease of placement in your Marine/Reef Tank.
• Recommended, depending on tank load, from 60 to 300 liters (15 to 79 US gal.) of sea water.
• Immersion depth: approx. 225 to 245 mm (8.9 to 9.7 in.)
• Skimmer cup volume: 0.2 liters (.05 in.)
• Air capacity: approx. 200 l/h (52.8 USgal./h),
• Energy consumption: approx. 5 W (max. 10 W)
• Power supply unit: 100-240V / 50-60Hz
• Cable length: 3 m (118.1 in.) up to the Turbelle^® controller
• Dimensions (L x W x H): 110 x 90 x 305 mm (4.3 x 3.5 x 12 in.)
• Magnet Holder up to a glass thickness of 12 mm (1/2").

The Tunze DOC Skimmer 9004 DC pulls dissolved organic waste out of the water before it breaks down into nitrates — see our guide to Protein Skimmers for how skimming fits into overall reef water quality.

What's in the Box

TUNZE publish a parts-supplied list for the Comline® DOC Skimmer 9004 DC, and this is it:

• Housing, with the upper plate, bottom plate, skimmer plate, skimmer panel, rear cover and a 19 mm cap
• Skimmer cup and skimmer cup cover — the foam reactor sits inside the cup, so lifting the cup out lifts the reactor with it
• Comline® Foamer
• Comline® silencer, with two foam inserts
• Magnet Holder, with its spacer
• Cleaning brush
• Power supply unit
• Turbelle® Controller, with its wall mount, three rotary knobs and a 16 mm protective cap

One difference from the mains 9004 is worth knowing before you order: TUNZE list the mechanical air control as a feature of the 9004 only, not of the 9004 DC. On this model you set foam wetness from the controller instead, which is also what gives the DC its adjustable output — useful, TUNZE note, in tanks heavily loaded with protein where the water foams.

The controller adds a cup cleaning button. It stops the pump so the cup can be lifted out without bubbles spilling into the tank, and restarts the pump by itself after about ten minutes if you have not pressed the button again. While the Foamer is stopped the air jet is rinsed with water, which TUNZE say significantly extends the intervals between full services.

Compatibility

TUNZE recommend the 9004 DC, depending on load, for 60 to 300 litres (15 to 79 USgal) of sea water, and separately give a figure of up to 180 litres for sensitive reef biotopes with hard corals. This is a marine skimmer; it is not intended for fresh water.

Where it will physically fit. It hangs inside the aquarium on its Magnet Holder, which takes glass up to 12 mm (1/2 in) thick. Immersion depth is roughly 225 to 245 mm (8.9 to 9.7 in), so the tank has to be deep enough to take it, and clear height is needed above the cup because part of the foam reactor lifts out with it. The compact housing is designed to keep light and algae off the reactor inside.

Allow for the controller as well as the skimmer: the 3 m cable is the run from the pump to the controller, and the controller then plugs into the power supply unit, which runs on 100–240 V / 50–60 Hz. TUNZE permit operation only with the original TUNZE power supply, and connection to third-party electronic switches or speed controllers is not permissible.

No flow pump should be aimed directly at the skimmer — that disturbs the foam.

TUNZE rate every DOC skimmer against a standard marine aquarium stocked with leather corals, and publish a reduction table for tanks that carry a more sensitive biotope. Their worked examples all use a skimmer rated for 1,000 litres:

• Leather corals, long-polyp corals and anemones — no reduction. TUNZE note that the dissolved-organic load in these tanks may be higher, and is sometimes even necessary, so the skimmer can be run at its full rated volume.
• Mixed leather and stony (LPS) corals — 40% reduction. TUNZE's example: a skimmer rated for 1,000 litres should be used on a tank holding about 600 litres at most.
• Predominantly small-polyp stony corals (SPS) — 60% reduction. A skimmer rated for 1,000 litres should be used on a tank holding about 400 litres at most. TUNZE add that these tanks should carry no phosphate or nitrate load worth mentioning, and that the skimmer is often the stand-alone filtration.
• SPS with a heavy fish population — 70% reduction. A skimmer rated for 1,000 litres should be used on a tank holding about 300 litres at most.
• Comline® skimmers used as contact skimmers on plankton breeding tanks — 70% reduction. TUNZE's example here is a Comline® skimmer rated for 1,200 litres on a tank holding about 360 litres at most.

TUNZE print this table on this model's own page. The rating to apply it to on this model is 60 to 300 litres.

Safety & Precautions

These are TUNZE's own safety instructions for the Comline® DOC Skimmer 9004 DC, from the manual supplied with it.

• Not designed for outdoor operation.
• Check that the operating voltage matches the mains supply before first use.
• Fit the mains plug higher than the unit, so water cannot run down the cable into the plug.
• Operation is permitted only with a residual-current circuit-breaker fitted, 30 mA maximum.
• Disconnect every electrical unit in the tank from the mains before working in the aquarium.
• Do not repair a damaged mains cable — replace the unit completely.
• Connecting the unit to third-party equipment such as electronic switches or speed controllers is not permissible.
• Maximum aquarium water temperature: +35 °C (95 °F).
• Keep the instruction manual.
• TUNZE state the device is suitable for users, children included, with limited physical, sensory or mental abilities, or without experience or prior knowledge, only where a responsible person provides suitable supervision or detailed instruction. Children should not be allowed to play with it.

Magnet Holder. TUNZE print a separate safety block for the magnet, and it is worth reading before the box is opened:

• Very strong magnet. Keep it out of reach of children.
• Never bring the upper and lower magnet halves together directly. Depending on the type, the halves clamp together on direct contact with about 30 to 200 kg (66 to 441 lbs) of force.
• Hold the magnet parts by the sides only. Never put a hand or fingers between the contact faces.
• It attracts metal parts and other magnets strongly at under 10 cm (3.9 in). Keep metal parts, other magnets, blades and knives further away than that while handling it.
• Keep at least 30 cm (11.8 in) from magnetically sensitive objects — pacemakers, data carriers, credit cards and keys.
• Always use the piece of polystyrene supplied when transporting the Magnet Holder.
• Heat above 50 °C (122 °F) destroys the magnet or its magnetic action.

Power supply unit. TUNZE's separate block for their power supplies:

• Not designed for outdoor operation.
• Place the power supply as far from the aquarium as possible, to prevent water damage.
• Operation is permitted only with a residual-current circuit-breaker fitted, 30 mA maximum.
• Mount it in a dry, well-ventilated position, away from heat sources.
• Ambient temperature in operation: 0 °C to +35 °C (32 °F to 95 °F).
• The Turbelle® Controller on the DC cable is susceptible to water and can be destroyed by it.
• TUNZE permit operation only with the original TUNZE power supply unit.

Warranty & Support

This product carries a 24-month manufacturer warranty from the date of purchase, covering material and manufacturing defects. TUNZE’s printed instruction manual is the document that governs here: their website currently quotes a longer period, but the manual supplied in the box states 24 months, and 24 months is the term we will honour.

What voids it, and what it does not cover. TUNZE name three exclusions: damage from inexpert handling, for which water damage is the example they give; technical modification carried out by the buyer; and connection to devices they have not recommended. The remedy under the guarantee is repair or replacement of the unit at TUNZE’s discretion, and consequential damage is explicitly excluded — on an aquarium that means the unit itself is covered and what happens in the tank when one fails is not. TUNZE also require a defective unit to come back in its original packaging with proof of purchase, so keep the carton and the foam for the two years rather than putting them out with the recycling.

Warranty support is handled by us directly. Message our WhatsApp support with your order number and we will diagnose the fault first — most cases are solved by replacing a single part, so you rarely need to send the whole unit. If the item does need to come back, it ships to our Delhi or Pune warehouse, whichever one served your order, and courier cost in both directions is borne by the customer. Your GST invoice is valid proof of purchase for the claim.

Returns & Replacement

Returns are accepted within 7 days of delivery, provided the item is unused and in its original packaging. Manufacturer-sealed items cannot be returned once the seal is broken, and sale-priced items are not refundable.

If your item arrives defective or damaged, message us on WhatsApp with your order number — or email us, if you would rather — and we will replace it. Approved replacements are delivered within 3 to 5 business days. Transit damage is covered by insurance on every shipment. If tracking shows delivered but nothing reached you, tell us within 72 hours, which is the reporting window Indian couriers allow. Damage caused during installation or use is not covered; replacement spares for such cases are chargeable.

Full terms are on our Cancellation & Returns page.