Posted by The Hot Tub Professor | SpaPartsNet.com
LX spa pumps are some of the most widely used pumps in the hot tub industry. You’ll find them across dozens of major brands because they are reliable, affordable, and built around standardized designs.
But that same standardization creates confusion when it’s time to replace one.
This guide breaks down:
• How LX pump numbers actually work
• Why brand numbers don’t mean it’s a different pump
• Mounting differences that cause ordering mistakes
• Why amperage matters more than horsepower
How LX Pump Part Numbers Are Structured
Most LX spa pumps begin with WUA.
Common horsepower classes include:
WUA100
WUA150
WUA200
WUA300
WUA350
WUA400
WUA500
The number refers to the horsepower class — but that’s only part of the story.
The characters before and after that number are critical.
Breaking Down a Full LX Pump Number
Example:
56WUA400II
Here’s what each section means:
56 → 56-frame motor
WUA → LX pump series
400 → 4 HP class
II → Two-speed motor
If you see:
56WUA300I
That means:
56-frame
3 HP class
Single-speed
Even one letter difference can change speed, mounting, or electrical load.
Why Spa Brands Make LX Pumps Look “Proprietary”
Many manufacturers use the same LX pump but assign their own internal part number.
That makes it look brand-specific — even when it’s identical.
For example:
Watkins part number 1431601-03
is the same pump as
LX 56WUA400II
The pump did not change. Only the catalog number did.
Other brands may list both numbers on the same label.
You may see something like:
56WUA400II
6500-352
6500-365
6500-367
Those additional numbers are internal catalog identifiers — not different pumps.
The Mounting Base Issue (Most Common Ordering Mistake)
This is where many pump replacements go wrong.
This mounting style is most commonly found in Jacuzzi®, Sundance®, and Dimension One® hot tubs.
In these systems, the LX pump often does not use a standard fixed mounting base.
Instead, it typically uses:
• A separate removable base plate
• A large worm-drive clamp
• A rotating motor mount design
This configuration allows the pump to be rotated into multiple positions, which is helpful in tight equipment bays.
If you order a standard LX pump with a fixed base — without realizing your original pump used this clamp-style mounting system — the replacement may not align correctly without modification or plumbing adjustments.
This is one of the most common causes of incorrect pump orders.
Always verify mounting style before purchasing a replacement.
Horsepower Is Marketing — Amperage Is Reality
This applies to all spa pumps.
Horsepower labels are often exaggerated.
Amperage tells you what the pump actually draws and what your system can safely handle.
When replacing a pump:
Ignore the advertised HP.
Match the amperage.
How to Read the Motor Label
Two-speed pump:
You’ll see something like:
10.0 / 3.5
10.0 amps = high speed
3.5 amps = low speed
For replacement purposes, use the high-speed amperage.
Single-speed pumps will list only one amperage value.
Real-World Amperage to Horsepower Reference (230V)
8 amps ≈ 1 HP
10 amps ≈ 2 HP
12 amps ≈ 3 HP
14 amps ≈ 4 HP
16 amps ≈ 5 HP
These are practical working averages.
Match the amperage as closely as possible to your original pump.
Why “Upgrading” Can Burn Things Up
Installing a higher-amp pump increases electrical load.
That can overload:
• Control boards
• Heater circuits
• Relays
• Wiring
• Plugs
• Breakers
Example:
Two 16-amp pumps = 32 amps
5.5 kW heater ≈ 21 amps
Total = 53 amps
Most spas are wired for 50 amps.
The math doesn’t support two true 5 HP pumps in most systems.
If someone told you that you have a 6 or 7 HP pump, it is almost certainly exaggerated labeling.
Special Warning for 115V Plug-and-Play Spas
True 2 HP 115V pumps are extremely uncommon.
Installing a higher amperage pump in a plug-in spa can:
• Melt plugs
• Overheat wiring
• Damage the control system
• Trip breakers constantly
• Shorten motor life
Never increase amperage in a 115V system.
Frame Size: 48 vs 56
Frame size must match exactly.
Measure across the back of the motor:
48 Frame → approx. 5¾ inches
56 Frame → approx. 6½ inches
Incorrect frame size affects alignment, mounting bolts, and wet end positioning.
Why SpaPartsNet Saves You Money
Hot tub manufacturers do not manufacture pumps.
They purchase pumps from companies like LX and apply proprietary part numbers.
At SpaPartsNet, we convert those proprietary numbers into the correct LX equivalent based on:
• Voltage
• Amperage
• Speed
• Frame size
• Mounting configuration
• Wet end orientation
You get the exact same pump without paying inflated branding prices.
Need Help Identifying Your LX Pump?
Before ordering:
Text clear photos of your motor label
Include mounting base photos
Tell us voltage and breaker size
We’ll confirm the correct replacement before you buy.
Text: 772-800-5445
Call: 844-500-4645
Email: dvillanueva@spapartsnet.com
SpaPartsNet.com
About The Hot Tub Professor
With over 25 years of hands-on spa repair and diagnostics experience, The Hot Tub Professor focuses on real-world electrical matching and compatibility — not marketing hype.
Important Disclaimer
SpaPartsNet is not affiliated with, endorsed by, or connected to Jacuzzi®, Sundance®, Dimension One®, Watkins®, Hot Spring®, Tiger River®, Caldera®, or Solana®. All brand names are used strictly for compatibility and identification purposes.