Octo 40mm HOB Output Sponges
SKU: ROP-OS-40
- Genuine OEM Direct Replacement: Authentic factory-spec open-cell output sponges designed specifically for large-body Reef Octopus Hang-On-Back (HOB) protein skimmers.
- Defoaming Microbubble Stopper: Physically disrupts and pops returning microbubbles to keep your aquarium display crystal clear.
- 3-Piece Value Pack Configuration: Arrives as a convenient triple-pack bundle to ensure complete replacement of your multi-stage defoaming device.
- Optimized High-Flow Porosity: Delivers efficient particulate capturing and bubble breaking without adding restrictive backpressure to the large 40mm plumbing line.
- Mechanically Balanced Densities: Calibrated explicitly to prevent splashing, stabilize return levels, and reduce salt spray around your tank rim.
- Saltwater-Safe & Reef Inert: Manufactured from 100% reef-safe, non-leaching poly-foam material that will not affect water chemistry or cause skimmer overflows.
Reef Octopus
Globally trusted for premium protein skimmers and pumps, engineered in-house for unmatched reef filtration performance.
Reef Octopus 40mm HOB Output Sponges (OCT-OS40)
The Reef Octopus 40mm HOB Output Sponges (SKU: OCT-OS40) are genuine factory-direct OEM replacement foam inserts distributed by CoralVue to optimize the return flow of your large-format hang-on back filtration loop. When heavy-duty external protein skimmers mix massive volumes of air and water under high pressure, tiny microbubbles naturally escape down the skimmer body alongside the clean water. Without mitigation, these tiny bubbles flow directly into your display tank, creating an unsightly "cloudy" look and irritating delicate corals. These specialized 40mm open-cell foam pads fit tightly inside your heavy return piping or dedicated Micro Bubble Stopper box to pop bubbles right before the water cascades back into your aquarium.
Over time, mechanical filtration sponges naturally accumulate organic detritus, trap floating food particles, and stiffen from calcification. When older 40mm foam inserts become overly compacted or clogged, they can cause high water volumes to back up inside the skimmer body, leading to unpredictable water level fluctuations and frustrating collection cup overflows. Swapping out a worn foam pad with a fresh factory-spec sponge immediately restores smooth, unimpeded return flow while shielding your display tank from microbubbles.
Key Features
True Drop-In Fitment: Precision cut to integrate seamlessly with standard 40mm metric plumbing profiles on large Reef Octopus return lines.
Premium Mechanical Interceptors: Functions as an effective final defensive layer to trap escaping floating debris and fine organic particulate.
Consistent Current Output: Retains its open, structural pore integrity over long-term saltwater submersion to prevent unexpected system backpressure.
Multi-Pack Convenience: Multi-piece kit format ensures you always have a fresh, clean sponge ready during intense equipment maintenance rotations.
Verified Hardware Compatibility
Reef Octopus Classic HOB Series: Classic 2000HOB (BH-2000).
High-Output Return Families: BH-300, BH-800SS, and BH-300F hang-on back models.
(Note: This set is sized specifically for oversized 40mm plumbing layouts. If you operate a smaller model like the Classic 100HOB, BH-90, or Classic 1000HOB, please source the alternative 25/32mm output sponge pack to match your narrower pipe dimensions).
What’s Included:
(3) Reef Octopus Replacement 40mm Open-Cell Output Sponges
(Note: Clear skimmer bodies, return pipe U-tubes, acrylic leveling screws, and defoaming box housings are sold separately).
Technical Specs:
Official Manufacturing Title: Reef Octopus 40mm Output Sponges for Classic HOB Protein Skimmers
SKU / Factory Part Identifier: OCT-OS40
Plumbing Class Accommodations: 40mm Inner Metric Return Lines / Micro Bubble Stoppers
Foam Material Composition: Saltwater-Inert Polyurethane Open-Cell Matrix
Primary Function: Mechanical Defoaming / Microbubble Suppression
- Turn off your protein skimmer's primary pump power line to completely halt water flow through the filtration column.
- Reach behind the aquarium rim and locate the 40mm acrylic microbubble stopper box or the return pipe attachment assembly.
- Extract the dirty, clogged output sponge from the return line using your fingertips or a pair of plastic aquascaping tweezers.
- Take a new OCT-OS40 replacement sponge and compress it slightly under a stream of fresh RO/DI water to clear out any manufacturing dust.
- Push the clean sponge down into the return pipe opening or defoaming device socket, making sure it sits flat without bundling.
- Re-activate your skimmer pump, check that water passes through the sponge freely, and confirm that microbubbles are being knocked down effectively.
Pro Tips:
- Rinse and Rotate to Prevent Nitrate Trapping. Because these output sponges act as mechanical screen filters on your return line, they will naturally catch escaping organic detritus and fish waste. If left unwashed for months at a time, this decaying organic matter will break down and turn into a source of unwanted nitrates and phosphates in your aquarium water column. To maintain low-nutrient parameters, pull the sponge out once a week during your regular maintenance, squeeze it out under running tap water, rinse it with RO/DI water, and put it back.
- Keep a Backup Sponge Dry for Fast Maintenance. Don't wait for your sponge to dry out while your skimmer sits turned off. Keep one of the extra sponges from this multi-pack clean and dry on your workbench. During your weekly cleaning routine, simply pull the dirty sponge out of the skimmer return line and drop the clean, dry backup straight into place. This allows you to restart your filtration system instantly while you take your time cleaning and drying the dirty foam insert for the next swap.
- Monitor Backpressure on High-Volume HOB Models. The large-body skimmers (like the BH-2000 or BH-300) push a high volume of water through their 40mm plumbing lines. Because the flow rate is aggressive, a heavily clogged sponge will cause water to back up much faster than it would on smaller models. If you notice the water level in your skimmer body creeping up toward the collection cup neck for no apparent reason, look at your output sponge first—it is usually the prime culprit indicating a cleaning is overdue.