Tunze DOC Skimmer 9430

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

• Recommended for salt water aquariums up to 3,000 liters (800 USgal.).
• Immersion depth from 100 to 200 mm (4 to 8 in.) without setting.
• Water flow rate: 1,500 l/h (396 USgal./h)
• Air capacity: 1,400 l/h (369 USgal./h)
• Energy consumption: 24 W, 230V/50Hz (32 W, 115V/60Hz)
• Skimmer cup volume: 2 liters (.5 USgal.)
• Dimensions of the skimmer cup including lid: ø215 x H.218 mm (8.46" x H. 8.58")
• Dimensions (L x W x H): 350 x 300 x 490 mm (13.8 x 11.8 x 19.3 in.)
• Headroom required to remove skimmer cup: minimum 71 mm (2.8 in.)

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The Tunze DOC Skimmer 9430 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 this skimmer, and this is it:

• Housing, with its disc
• Skimmer cup and skimmer cup lid — the cup contains the foam reactor, so cleaning the cup cleans the reactor at the same time
• Hydrofoamer Silence, the pump that makes both the foam and the water circulation
• 170 mm outlet pipe
• Post-filter, and the 300 µm post-filter bag that goes in it
• Cleaning brush

The Hydrofoamer supplied with this model is the larger one in the range, matched to the 1,400 l/h air figure on the specification above.

Two things TUNZE list as accessories rather than contents. The strainer for the Hydrofoamer, which keeps leaves and coarse debris out of the dispersant, is not in the scope of delivery. Nor is the acoustic filter mat they suggest standing the unit on. The hose clamp used to throttle the air during the first days of running is supplied.

Compatibility

TUNZE recommend this skimmer for salt water aquariums up to 3,000 litres (800 USgal). This is a marine skimmer; it is not intended for fresh water.

Where it will physically fit. This is a cabinet-filter skimmer: it stands in a sump rather than hanging in the display tank. TUNZE prepare it at the works for a variable water level of 100 to 200 mm (3.9 to 7.8 in), and no setting has to be changed inside that window. The body is 350 × 300 × 490 mm. Clear height above it matters as much as footprint — the skimmer cup lifts vertically out and part of the foam reactor comes with it, and the cup and post-filter both need to stay easy to reach for weekly cleaning.

Stand it upright, in a zone of calm water. TUNZE are specific that a drain outlet or an air ejector close by will disturb the formation of foam, and that standing upright is what decides both the efficiency and how quietly it runs. If noise matters, they suggest standing it on a filter mat of about 300 × 400 mm and 50 mm thick, watching the water level in the filter tank as you do. They also note that this skimmer holds its setting when switched off, so it can be run on a timer — eight hours a day off is their example — provided you are not already running it at the bottom of its recommended range for the tank.

The post-filter takes other media if you want it to — TUNZE name wadding, activated carbon and phosphate absorber — and a ring inside it sets the outlet-pipe height, which is how you tune the foam: raise it for wetter foam, lower it for drier. Air output should always stay at maximum. Set the height so phase water cannot get into the air passage, or skimming falls off sharply.

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 their DOC Skimmer pages. The rating to apply it to on this model is up to 3,000 litres.

Safety & Precautions

These are TUNZE's own safety instructions for the DOC Skimmer 9430, 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.

Minimum water level. The level must not fall below 100 mm (3.9 in). Below it the Hydrofoamer Silence can be damaged — the motor overheats, or the pump is damaged mechanically by running dry. TUNZE state plainly that this is a warranty exclusion.

If you dose ozone. TUNZE describe an ozone connection for this skimmer and attach a warning to it: uncontrolled, continuous ozone use can damage health and can damage the electrical and plastic parts of the unit, embrittling them. Synthetic materials in prolonged contact with ozone become brittle and liable to break. Their own recommendation for a hard-coral reef aquarium is 1 mg of ozone per 100 litres (26.4 USgal).

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.