
Genuine Maytronics part · Filters
Ultra-Fine Filter Assembly, S2
Part number 9991458-ASSY · UPC 7290018363362 · 1 year part warranty
Genuine Maytronics replacement ultra-fine filter basket for Dolphin S200, Dolphin T55i and Dolphin Active 2000.
$96.99 MSRP
Out of stock
About this part
What it does and when to replace it.
This genuine Maytronics part replaces the S2 ultra-fine filter basket in compatible Dolphin robots. It captures fine debris from the water as the robot cleans.
The confirmed fit list includes Dolphin S200, Dolphin T55i, Dolphin Active 2000, Dolphin Premium 2000, Dolphin T2000, Dolphin S2000, Dolphin Active 3000, Dolphin Premium 3000 and Dolphin T3000. Identify this replacement by part number 9991458-ASSY. It is not currently stocked by Poolbots. Contact Poolbots' pool experts by live chat or phone for help identifying the right part.
- Check your robot's model against the confirmed fit list before requesting part 9991458-ASSY.
- Rinse collected debris from the basket after cleaning and inspect the filter material for damage.
Compatibility
Fits these Dolphin robots.
Confirmed by Maytronics' compatibility checker and each robot's own spare-parts list.
Also listed by Maytronics for: S200.
Do it yourself
How to replace it at home.
Switch off and unplug the power supply.
Remove the robot from the pool and open the filter compartment.
Lift out the old basket and clear loose debris from the compartment.
Place the replacement basket in the compartment and check that it is seated properly.
Close the filter compartment before returning the robot to the pool.
Step-by-step answers for this kind of part
How do I replace the filter panels on my Dolphin robot?Video15 min
Find your model below, then follow its video and instructions. The panel removal and installation steps vary by filter design.
S50 (Cayman, T15, T25, Active 10, Escape, Encore, E20, E25) & S100 (Advantage, Proteus DX3, Saturn, Echo, Nautilus CC, Active 15, Escape, Liberty 200/300/400)

Step 1Remove the old filter panels
- Lift the filter cover open.
- Take the filter basket out of the robot.
- Press the plastic release at the top of the filter's wide side, then lift out the released panel. The narrow side panels come out easily. The front and back panels are secured with screws, so use a Phillips-head screwdriver to release them.
- Follow the same process for the opposite side panel.
Step 2Install the replacement panels
- Slide a replacement panel into the basket.
- Push the panel against the frame until it clicks into place.
- Fit the other side panel the same way.
- With both panels in position, clip the filter's bottom section back into place.
S200 (E30, Advantage Ultra, Active 20, Quantum, T30, Proteus DX4, Triton PS) / S300 (E35/E35i, Proteus DX5i, Active 30, T35/T45, Premium 40, Explorer E30, E40i, Active 30i, T55i) / S400 (E50i, Active 50, Explorer E50) / Liberty 600

Step 1Remove the old filter panels
- Lift the filter cover open.
- Take the filter basket out of the robot.
- Press the plastic release at the top of the filter's side, then lift out the panel that releases.
- Work through the remaining narrow and wide panels using the same method.
Step 2Install the replacement panels
- Set the bottom edge of a replacement panel into the filter's lower rail.
- Push the panel into the frame so it clips into the filter.
- Press it against the frame until you hear it click.
- Fit each remaining narrow and wide panel the same way.
Premier/Dx4 (Bag filter)

Filter bag setup for Dolphin Premier
- Turn the robot upside down so you can reach the filter area.
- Release the clips underneath the filter assembly.
- Lift the assembly out of the robot.
- If the white filter screen is not already fitted, secure it with the two screws.
- Check that the filter bag sits securely on the assembly's guard rails.
- Put the filter bag assembly back in, following the guide and video.
Filter cartridge assembly setup for Dolphin Premier
- Turn the robot upside down so you can reach the filter area.
- Release the clips underneath the filter assembly.
- Lift the assembly out of the robot.
- Make sure the white filter screen is not installed for this setup.
- Follow the guide and video to reinstall the assembly.
- Fasten the clips underneath the assembly to secure it.
M250 (Dx3, Nautilus CC Plus)

Step 1Prepare the filter cartridges
- Lift the filter covers and take the cartridges out of the robot.
- Release the clips at the top of each cartridge.
- Inspect the non-return flap for debris.
- Check that the frame is clean before fitting replacement panels.
Step 2Fit the replacement panels
- Seat the locating tabs along the bottom of each panel in the matching grooves on the base frame.
M400/M500 (Sigma, Nautilus CC Supreme, Aquarius XL, Oasis)

Step 1Prepare the filter cartridges
- Lift the filter covers and take the cartridges out of the robot.
- Release the clips at the top of each cartridge.
- Inspect the non-return flap for debris.
- Check that the frame is clean before fitting replacement panels.
Step 2Fit the replacement panels
- Seat the locating tabs along the bottom of each panel in the matching grooves on the base frame.
M600/M700 (Active 60, E60i, Premium 60, Explorer E70)

Step 1Remove the old filter panels
- Lift the filter cover open.
- Take the filter basket out of the robot.
- Press the plastic release at the top of the filter's side, then lift out the panel that releases.
- Work through the remaining narrow and wide panels using the same method.
Step 2Install the replacement panels
- Set the bottom edge of a replacement panel into the filter's lower rail.
- Push the panel into the frame so it clips into the filter.
- Press it against the frame until you hear it click.
- Fit each remaining narrow and wide panel the same way.
Replacement panels and filter care
You can purchase replacement filter panels from Poolbots. Before ordering, confirm that the panel part number matches your robot. For help choosing the correct panels, contact Poolbots' pool experts by live chat or phone.
Additional references:
Specifications
Size & Dimension
- Gross Weight
- 2.007 lb
General Info
- Warranty (years)
- 1
- UPC
- 7290018363362
Questions
Ultra-Fine Filter Assembly, S2, answered.
Does this filter basket fit the Dolphin S200?
Yes. Dolphin S200 is on the confirmed compatibility list for part 9991458-ASSY. For help checking another model, contact Poolbots' pool experts by live chat or phone.
Can I order this part from Poolbots?
This part is not currently stocked by Poolbots. Contact Poolbots' pool experts by live chat or phone for help confirming the replacement you need.
What warranty is listed for this part?
Maytronics lists a one-year warranty for this replacement filter assembly.




















