MD-20RT - 492 GPH Japanese

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Why does BRS recommend this?

Anytime we need an external pump the Iwaki Japanese motors are our first choice.  There are cheaper options that work just fine, however when it comes to noise the Iwaki Japanese external pumps are class leaders and for any area where noise a concern and space is limited. The Japanese Iwaki pump is the way to go.


External pump from Iwaki, the world leader in small magnetically coupled centrifugal pump technology. MD stands for Magnetic-Drive. High quality external pump with years of research and development behind its design. Iwaki pumps offer high pressure rates in a durable, compact pump. Easily tailor pump applications because of the numerous motor/pump configurations. Japanese-made motor is designed especially for aquatic applications. Super quiet and energy efficient.


MD Series – Japanese Motor

  • Japanese motor is made from cast aluminum with a cast end bell
  • Japanese model uses a custom pump design specifically for aquatic applications
  • Japanese pumps run cooler to the touch and slightly quieter, due to the thicker material

Note: The Iwaki MD pumps' power cords do not come with the plug pre-wired.



  • Japanese Motor
  • Max Flow: 492 GPH
  • Max Head: 14.1 Ft
  • ¾” Inlet(MPT)/ ¾ ” Outlet(MPT)
  • Max Amps: .48
  • Motor Output: 1/38 HP


Iwaki Flow and Tech Specs


Quick Compare - Iwaki MD Pumps (Japanese Motors)

Model Power Usage Maximum Flow Maximum Head Connections

Iwaki MD-20RT


492 GPH

14.1 ft

Hose 5/8” NPT ¾”

Iwaki MD-20RXT


822 GPH

8.2 ft

Hose 1” NPT 1”

Iwaki MD-30RT


600 GPH

17.7 ft

Hose ¾” NPT ¾”

Iwaki MD-30RXT


1140 GPH

13.5 ft

Hose 1” NPT 1”

Iwaki MD-40RT


822 GPH

21.3 ft

Hose ¾” NPT ¾”

Iwaki MD-40RXT


1344 GPH

15.4 ft

Hose 1” NPT 1”

Iwaki MD-55RLT


1104 GPH

26.9 ft

Hose 1” NPT 1”

Iwaki MD-70RLT


1536 GPH

31.8 ft

Hose 1” NPT 1”

Iwaki MD-100RLT


2136 GPH

39.0 ft

Hose 1” NPT 1”

More Information
Input Size 0.75" (3/4 in.)
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Product Questions

I've noticed that after 1.5 years, my 20RT is precipitating salt out the sides, indicating to me that it may be leaking. I plan to remove it and clean it soon, but if the gasket has gone out, where can I get a replacement? Is it as simple as getting a new o-ring at the hardware store, or will I need to order a part from the manufacturer?
Question by: Eric Anderson on Jun 9, 2017, 11:19 AM
It does sound like the seals may be aging. We don't currently have replacement components for these pumps. For assistance with parts, we recommend reaching out to Iwaki directly.

Iwaki – 508-429-1440 service@iwakiamerica.com

Happy reefing!
Answer by: Zack on Jun 13, 2017, 11:19 PM
A lot of great information on this pump. My space is limited and would like the dimensions on the unit.
Question by: Matt Lee on Mar 14, 2016, 10:23 AM
Great question!
This pump will have dimensions of:
8" x 4.17"x 4.19"
Feel free to let us know if you have any further questions!
Answer by: Connor on Mar 15, 2016, 3:51 PM