If you own a Dolphin Nautilus robotic pool cleaner, you know the struggle of fine debris that slips through standard filters. Algae spores, sand, and tiny particles can leave your pool looking hazy. Upgrading to a dedicated Dolphin Nautilus ultra fine filter solves this, trapping particles as small as 10 microns. In this guide, we evaluated eight top aftermarket and compatible filters to help you choose the best option for your Nautilus model. Whether you need a basket for the original Nautilus CC or cartridge panels for the Nautilus CC Plus, we have you covered. For a broader look at compatible options, check our roundup of Dolphin pool cleaner filters on Amazon.
Pros
- High-efficiency microfiltration captures fine dirt, sand, and leaves for pristine pool water.
- Works with a wide range of popular Dolphin robot models, reducing the need for multiple filter types.
- Easy to clean and maintain with no special tools required.
- Affordable price compared to manufacturer replacement filters.
- Solid build quality with lightweight yet sturdy plastic construction.
Cons
- Not compatible with Dolphin Nautilus CC Pro or CC Supreme models, limiting its use for newer variants.
- Older versions of Active 10 or S50 may require removal of a plastic piece for proper fit, which could be inconvenient for some users.
- As an aftermarket part, it may not perfectly match OEM quality or warranty coverage.
The Ulticor Ultra Fine Filter Basket is an aftermarket replacement designed specifically for a wide array of Dolphin robotic pool cleaners. It is an ideal choice for pool owners who already own compatible models such as the Dolphin S50, S100, Active 10/15, Echo, T15, T25, Proteus DX3, Saturn, Cayman, Escape, and others. This basket is not intended for the Nautilus CC Pro or Supreme versions, so buyers should verify compatibility before purchasing.
What sets this filter apart is its microfiltration technology, which captures even the tiniest debris particles. In real-world use, this translates to a noticeably cleaner pool with clearer water, as fine dirt, sand, and pollen are effectively trapped. The basket is easy to rinse and clean every four to six weeks, maintaining peak performance without hassle. Users report that it fits snugly and works reliably cycle after cycle.
The design is straightforward: a white, lightweight plastic basket measuring roughly 9x5x7 inches. Build quality feels solid for an aftermarket part, though it may not have the exact finish of an OEM component. The inclusion of installation tips for older Active 10 or S50 units (which may need a small internal plastic piece removed) shows attention to compatibility details. A video guide is available upon request to assist with that adjustment.
Potential drawbacks are mostly centered on fitment limitations. Owners of Nautilus CC Pro or Supreme will need to look elsewhere. Also, the need to modify older robots could be a minor inconvenience for those not comfortable with simple DIY tasks. However, for the vast majority of compatible users, installation is plug-and-play.
Overall, the Ulticor Ultra Fine Filter Basket offers excellent value for money. It delivers superior filtration at a lower price than official replacements, while covering a wide range of popular Dolphin models. If you own one of the listed robots and want to keep your pool sparkling clean without breaking the bank, this filter is a smart buy.
Pros
- Ultra-fine 10-micron filtration for superior water clarity
- Reusable and easy to clean with minimal maintenance
- Durable ABS construction lasts 2-3 years
- Fits multiple Dolphin and compatible pool cleaner models
- Backed by a 1-year warranty
Cons
- Not compatible with Nautilus CC Pro or CC Supreme models
- May require removing a plastic piece in older Active 10 or S50 robots for proper fit
- Zero customer reviews available at launch, so long-term reliability is unverified
The SUNRRA Ultra-Fine Filter Basket is a replacement part designed specifically for a wide range of Dolphin and compatible robotic pool cleaners. It is the ideal upgrade for pool owners using models like the Dolphin Nautilus CC, Proteus DX3, Explorer E20, Active 10/15, and many others. By replacing your worn or clogged filter basket with this ultra-fine variant, you can achieve noticeably clearer pool water.
The standout feature of this filter basket is its ability to capture particles as small as 10 microns. This includes fine dust, algae, and silt that standard filters often miss. As a result, your pool water remains crystal clear with less reliance on chemical flocculants or clarifiers. The reusable design means you simply rinse it every 4 to 6 weeks, saving money on disposable filters and reducing waste.
Constructed from durable ABS plastic, the basket is built to withstand the harsh pool environment and frequent cleaning cycles. SUNRRA claims a lifespan of 2 to 3 years with proper maintenance. The filter fits securely into the designated robot models, ensuring a tight seal to prevent bypass of unfiltered water. However, note that for older versions of the Active 10 or S50, you may need to remove an internal plastic piece for full compatibility.
One limitation is that this basket does not work with the Nautilus CC Pro or CC Supreme models, so check your robot's model before purchasing. Additionally, there are currently no customer reviews to confirm real-world performance, though the product comes with a 1-year warranty for peace of mind. The slightly higher initial cost may be offset by long-term durability and improved filtration.
For pool owners with compatible robotic cleaners, the SUNRRA Ultra-Fine Filter Basket is a worthwhile investment. It offers superior particle capture, easy maintenance, and a robust build. While compatibility caveats exist for specific models, most users will appreciate the enhanced water clarity. If you are looking to maximize your pool cleaner's performance, this replacement basket is a solid choice.
Pros
- Designed to replace Maytronics 9991432-R4 for many Dolphin robotic cleaner models
- Ultra fine pleated media traps both small particles and larger debris effectively
- Reinforced ABS frame keeps the filter stable during operation
- 4 pack provides good value and a longer interval before you need to reorder
- Simple maintenance with periodic rinsing every 4 to 6 weeks
Cons
- Not compatible with many Dolphin models such as Nautilus CC, M600, S200, Triton PS, and others, so check fit carefully before buying
- Aftermarket part is not an original Maytronics product, which may matter to some buyers
- No customer reviews are available yet, so long-term real-world performance is less proven
The Funmit M400 Ultra Fine Cartridge Filter is a 4 pack replacement designed for the Dolphin Nautilus CC Plus and a wide range of compatible robotic pool cleaners. It replaces Maytronics part 9991432-R4, making it a practical option for pool owners who want dependable filtration without the premium price of the OEM part.
The standout feature is the ultra fine pleated filter paper, which captures sand, leaves, hair, and other debris while maximizing surface area. The heavy duty ABS plastic frame keeps the pleats stable during operation and prevents the filter from deforming under water flow, so the cleaner maintains strong suction and consistent performance.
Maintenance is straightforward: rinsing the filter every 4 to 6 weeks is enough to keep it working well, and with proper care each filter can last 2 to 3 years. The 4 pack is especially convenient for owners who clean frequently or have a large pool, because there is always a fresh filter on hand.
The main drawback is compatibility. This filter does not fit several popular Dolphin models, including Nautilus CC, M600, S200, Triton PS, and others, so it is essential to verify your pool cleaner model before purchasing. As an aftermarket part, it also does not carry the original manufacturer branding, though the build quality is solid for the price.
Overall, the Funmit M400 filter replacement offers strong filtration, durable construction, and good value for owners of compatible Dolphin robotic cleaners. If you confirm the fit first, this 4 pack is a smart, budget friendly way to keep your pool clear all season.
Color: White
Dimensions: 10.5 x 6.375 x 10.5 inches
Package includes: 4 cartridge filters
Replaces Maytronics part 9991432-R4
Compatible with Dolphin Nautilus CC Plus, M400, M500, M200, M4, M5, Wave 65, Wave 90, C3, C4, Oasis Z5i, Aquarius XL, Liberty, Odyssey, Sigma, Triton Plus (old)
Buying Guide for Dolphin Nautilus Ultra Fine Filters
Compatibility with Your Dolphin Model
Not every ultra fine filter fits every Nautilus variant. The original Nautilus CC uses a filter basket (part #9991460-R1), while the Nautilus CC Plus and Supreme use cartridge panels (part #9991432-R4). Before purchasing, confirm your cleaner model. Many aftermarket options, like the Ulticor Ultra Fine Filter Basket Compatible, explicitly list compatible robots including Nautilus CC but not the Plus or Supreme. Conversely, filters like the M400 Ultra Fine Cartridge Filters Compatible fit the Nautilus CC Plus only. Always double-check the compatibility list.
Filtration Efficiency and Micron Rating
The core purpose of an ultra fine filter is capturing tiny debris. Look for filters with a micron rating around 10 to 50 microns. The Doule King Ultra-Fine Filter Basket uses a 50-micron 3D mesh that claims 60% better filtration than standard baskets. SUNRRA filters for the Nautilus CC Plus use pleated media that trap particles down to 10 microns. Higher pleat counts also improve surface area, reducing clogging and maintaining water flow. For more insights on aftermarket options, browse our guide to Dolphin aftermarket replacement filters.
Durability and Maintenance
Most premium filters are made from UV-resistant ABS plastic and washable mesh or pleated paper. Models like the Poolzilla Ultra-Fine Filters and Kerneed M400 cartridges are built to last 2 to 3 seasons with proper care. Rinsing every 4 to 6 weeks with a garden hose keeps them performing. Avoid abrasive cleaners that can damage the filter media. Durable construction also prevents cracking from pool chemicals and sunlight.
Ease of Installation
All the filters we evaluated are designed as direct replacements. Basket filters snap into place without tools; cartridge panels slide into the cleaner’s tray. However, some older Dolphin models (like earlier Active 10 or S50) may require removing a small plastic piece inside the robot for proper fit. The Ulticor and SUNRRA brands provide clear instructions. If you are unsure about your model, consult the Dolphin robotic pool cleaner filter basket guide for detailed compatibility.
Final Thoughts
After reviewing all eight options, we recommend two top performers for different needs. For owners of the original Dolphin Nautilus CC or other basket-compatible robots, the Ulticor Ultra Fine Filter Basket Compatible offers an exceptional blend of high-quality microfiltration, wide compatibility, and a near-perfect rating. If you have a Nautilus CC Plus or Supreme and want a budget-friendly pack that delivers consistent results, the M400 Ultra Fine Cartridge Filters Compatible from Kerneed provide outstanding value with four panels that capture even the finest particles. Either choice will keep your pool sparkling clean throughout the season.
Related Guides
- Best Pool Robot Filter Basket for Algae in 2026
- Dolphin Nautilus Filter Basket
- Dolphin Ultra Fine Filter Review
Frequently Asked Questions
Are ultra fine filters compatible with Dolphin Nautilus CC Plus?
Yes, but only cartridge-style filters that replace part #9991432-R4 work with the Nautilus CC Plus and Supreme. Basket filters like #9991460-R1 are for the older Nautilus CC. Always verify your model number before ordering. For a full compatibility list, see our Dolphin OEM replacement filters guide.
How often should I clean a Dolphin ultra fine filter?
Rinse the filter every 4 to 6 weeks with a garden hose. If your pool is especially dirty or you have fine debris like algae, you may need to clean it weekly. Regular rinsing maintains optimal water flow and extends the filter’s lifespan to 2 to 3 years.
What is the difference between standard and ultra fine filters for Dolphin cleaners?
Standard filters typically capture larger debris like leaves and twigs. Ultra fine filters use tighter mesh (10 to 50 microns) to trap sand, silt, algae, and even microscopic particles. Upgrading to an ultra fine filter dramatically improves water clarity, especially for pools prone to fine sediment.
Can I use aftermarket filters for my Dolphin robot?
Yes, many reputable aftermarket brands like ULTICOR, SUNRRA, Kerneed, and Funmit offer filters that match or exceed OEM quality. They are made from compatible materials and dimensions, and they cost less than genuine Dolphin parts. Just confirm compatibility with your specific model before buying.
For more replacement options, visit our Replacement Filters category.
