---
product_id: 220087980
title: "U3 Underwater Filter"
brand: "fluval"
price: "A$299"
currency: AUD
in_stock: true
reviews_count: 13
category: "Fluval"
url: https://www.desertcart.com.au/products/220087980-u3-underwater-filter
store_origin: AU
region: Australia
---

# 3-way adjustable flow control whisper-quiet operation 3-stage filtration system U3 Underwater Filter

**Brand:** fluval
**Price:** A$299
**Availability:** ✅ In Stock

## Summary

> 💧 Elevate your aquarium’s ecosystem with precision flow and pristine clarity!

## Quick Answers

- **What is this?** U3 Underwater Filter by fluval
- **How much does it cost?** A$299 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.au](https://www.desertcart.com.au/products/220087980-u3-underwater-filter)

## Best For

- fluval enthusiasts

## Why This Product

- Trusted fluval brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Effortless Maintenance:** Flip-top lid design ensures quick cartridge swaps without hassle.
- • **Versatile Installation:** Fits vertically or horizontally, perfect for creating currents or decorative water features.
- • **Customizable Flow Dynamics:** Three distinct flow settings tailor water movement to your aquarium’s unique ecosystem.
- • **Precision 3-Stage Filtration:** Combines mechanical, chemical, and biological filtering for crystal-clear water.
- • **Silent & Efficient Performance:** Operates quietly to maintain a peaceful environment while maximizing filtration.

## Overview

The Fluval U3 Underwater Filter is a compact, battery-powered filtration system designed for 20-40 gallon aquariums. Featuring a 3-stage filtration process including biomax biological media, it offers adjustable 3-way flow control for tailored water circulation. Its quiet operation and versatile installation options make it ideal for fresh, marine, and reptile tanks, ensuring optimal water quality with minimal maintenance.

## Description

Fluval U3 underwater filter provides complete and efficient 3-stage filtration, including biomax biological filtering, to create superior aquarium water quality. The U3 filter includes practical and versatile features, making it ideal for application in fresh, marine and reptile environments. The filter provides the option of setting the flow output in 3 different positions, a key benchmark in underwater filtration. The adjustable 3-way flow control feature lets you position the water flow output to meet your specific needs. The Top Output setting provides maximum circulation and oxygenation, the Integrated Spray Bar setting provides a gentle, even flow for planted aquariums, and the Bottom Output setting is for deepwater agitation. The filter also has a convenient flip-top lid that allows quick and easy access to the filter cartridge for maintenance or replacement. The filter can be installed vertically against the aquarium wall to create currents or customized flow patterns; it can be placed horizontally in shallow water tanks; or it can be used to create decorative features, such as waterfalls.

Review: An excellent filter - I had a cloudy aquarium with a filter priced 400 rs. It had to run for a week to make the water clear and the water flow was strong which made the fish hard to swim on their own. But this filter does magic. With in some hours after installation, the water became crystal clear. The flow is very smooth too.
Review: Five Stars - Good Product. Effectiveness: 10/10 Price: 4/5 - slightly pricey

## Features

- Filters debris and provides optimal biological filtration
- Simple to install and maintain
- Silent and efficient
- Ideal supplemental or stand-alone filter or for installations where external filtration is not possible
- Comes with 3-way flow control with adjustable output, 2 foam pads, 2 poly/carbon cartridges and 65 grams biomax
- Ideal for 20-40 gallon environments

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Brand | Fluval |
| Special Feature | Biological Filtering, Adjustable Flow Control |
| Product Dimensions | 30L x 15W x 30H Centimeters |
| Package Information | box |
| Installation Type | Filter |
| Power Source | Battery Powered |
| Item Weight | 798 Grams |
| Model Name | A475 |
| Lower Temperature Rating | 100 Degrees Celsius |
| Maximum Flow Rate | 100 Cubic Centimeters Per Minute |
| Supported Water TDS Level Maximum (PPM) | 300 |
| UPC | 015561104753 015561104869 |
| Global Trade Identification Number | 00015561104753 |
| Manufacturer | Rolf C. Hagen (USA) Corp. |
| Country of Origin | USA |
| Item model number | A475A1 |
| ASIN | B001TKZ51E |

## Product Details

- **Brand:** Fluval
- **Special Feature:** Biological Filtering, Adjustable Flow Control
- **Product Dimensions:** 30L x 15W x 30H Centimeters
- **Material:** Plastic
- **Capacity:** 150 litres

## Images

![U3 Underwater Filter - Image 1](https://m.media-amazon.com/images/I/71x9jM2Xh2L.jpg)

## Available Options

This product comes in different **Size** options.

## Questions & Answers

**Q: Currently have a 10gallon but will upgrade shortly to a 30ish for a yellow eared turtle.  Does this sit on the bottom where it could suck in the food and waste that collects on the bottom where my river rocks are?  It has proven hard to get that out and the pleccu is not cleaning it up as of now.**
A: Mine is laying on the bottom of my tank and i have never had it sitting upright. I can tell you it does pretty well sucking everything up. However, i usually have one spot in the tank, right underneath the filter where debris sits. When I need to water change I just make sure I get the debris out with a fish net. That seems to work pretty well. It is the best filter I have had so far (with a turtle that has killed 4 filters), just make sure to clean the motor fan with every water change or filter media change.

**Q: Does the U4 filter have space to add activated carbon pellets?**
A: Yes it can, in the center of the filter there a removeable plastic cage. I put a small Chemi Pure bag in it. But I didn't care for this filter and not cause it didn't work. But I was wanting something more as a skimmer type filter and I wasn't getting enough flow out this filter unit. But it did work, if your running this on a smaller tank say no 30 gal freshwater ok. I was running it on a 29 gal reef tank with lots of live rock and it couldn't push enough water around it. But it did filter the water good.

**Q: Do all 3 outputs work at the same time?**
A: No, you have to pick a setting. I use mine for moving water in the bottom of my tank. It also seems to be he strongest setting out of the 3 choices

**Q: Can I change the direction of the water coming out of the nozzles? For example directing it upwards instead of horizontal.**
A: There's a small directional piece on the end of each nozzle you can turn to minimally direct the flow - but not nearly that much.

## Customer Reviews

### ⭐⭐⭐⭐⭐ An excellent filter
*by R***N on 13 March 2017*

I had a cloudy aquarium with a filter priced 400 rs. It had to run for a week to make the water clear and the water flow was strong which made the fish hard to swim on their own. But this filter does magic. With in some hours after installation, the water became crystal clear. The flow is very smooth too.

### ⭐⭐⭐⭐⭐ Five Stars
*by D***J on 7 February 2018*

Good Product. Effectiveness: 10/10 Price: 4/5 - slightly pricey

### ⭐⭐⭐⭐ Good, not great
*by V***S on 10 July 2020*

Underwhelming. Had read a lot of great reviews. But not delighted. Good design, no doubt. Easy to install, clean etc. Powerful motor. U3 working well in a 25 Gallon In my opinion, filter media volume is just too small. Mechanical filtration is inadequate and bio media is too small in volume. Sponge filter choked up in a week and when I pulled the tray out it spilled a lot of muck back into the water. Again, good product, but not great.

## Frequently Bought Together

- Fluval U3 Underwater Filter – Designed for Freshwater and Saltwater Aquariums, Also Ideal for Terrariums and Turtle Tanks
- Nosiny 20 Pieces Filter Foam Pad Compatible with Fluval U3 Underwater Sponge Aquarium Underwater Filter Accessories Compatible for Aquarium, Fish Tank
- Fluval U3 Underwater Filter Poly/Carbon

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*Product available on Desertcart Australia*
*Store origin: AU*
*Last updated: 2026-02-24*