---
product_id: 2119026
title: "Penn-Plax Undergravel Aquarium Filter for 40-55 Gallon Tanks – Four 11.25” x 11.25” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks (CFU55)"
price: "31548 Ft"
currency: HUF
in_stock: true
reviews_count: 8
url: https://www.desertcart.hu/products/2119026-penn-plax-undergravel-aquarium-filter-for-40-55-gallon-tanks
store_origin: HU
region: Hungary
---

# Air-driven filtration & aeration 4 filter plates 11.25" x 11.25" each Biological, chemical & physical filtration Penn-Plax Undergravel Aquarium Filter for 40-55 Gallon Tanks – Four 11.25” x 11.25” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks (CFU55)

**Price:** 31548 Ft
**Availability:** ✅ In Stock

## Summary

> 💧 Elevate your aquarium game with the ultimate undergravel filter—clean, clear, and effortlessly cool!

## Quick Answers

- **What is this?** Penn-Plax Undergravel Aquarium Filter for 40-55 Gallon Tanks – Four 11.25” x 11.25” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks (CFU55)
- **How much does it cost?** 31548 Ft with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.hu](https://www.desertcart.hu/products/2119026-penn-plax-undergravel-aquarium-filter-for-40-55-gallon-tanks)

## Best For

- Customers looking for quality international products

## Why This Product

- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Quad-Plate Power:** Four large 11.25" x 11.25" plates maximize filtration surface area for tanks 40-55 gallons.
- • **Complete Setup Included:** All essential components included—plates, lift tubes, airline tubes, connectors, and carbon cartridges.
- • **Triple-Action Filtration:** Combines biological, chemical, and physical filtration for crystal clear, healthy water.
- • **Dual Function Filter + Aerator:** Simultaneously filters and oxygenates your aquarium with one streamlined system.
- • **Effortless Clarity, Minimal Fuss:** Air-driven system means fewer moving parts for easy maintenance and a sleek tank look.

## Overview

The Penn-Plax Clear-Free Premium Undergravel Aquarium Filter is an air-driven filtration system designed for 40-55 gallon freshwater and saltwater tanks. Featuring four 11.25" x 11.25" filter plates, it delivers biological, chemical, and physical filtration while aerating your tank simultaneously. Its minimalist design reduces moving parts for easy maintenance, and the included components provide a complete setup for efficient, long-lasting water clarity.

## Description

PENN-PLAX presents the Clear-Free Premium Under Gravel Aquarium Filter. Those who’ve been around the aquatic block for a while know that Under Gravel Filters (UGFs) are a testament of time. This Filter is air driven and utilizes an Air Pump (not included) to cycle crystal clear water throughout your aquarium, while keeping a crisp and neat look inside. This means there’s less “moving parts,” making for simplistic and easy maintenance. It’s suitable for most suitable for most 40 – 55 gallon aquariums, and is safe for Freshwater and Saltwater setups.Biological, Chemical, and Physical Filtration: As air is pushed through the Air Stones and rises through the Lift Tubes, water is gently suctioned through gravel and the filter plates, allowing both air and water to pass through the Filt-a-Carb Activated Carbon Cartridges. When water continues to be drawn through, anaerobic bacteria collects and colonizes within the gravel and filter plates.Also Aerates Your Tank: Since the Clear-Free Premium Under Gravel Filter is air driven through the use of Air Stones and an Air Pump (not included), it also aerates your tank. In essence, your aquarium is being filtered and aerated at the same time, though the same system! It’s a filter and bubbler in 1!Items Included: The Clear-Free Premium Under Gravel Filter includes 4 Filter Plates 4 Adjustable Lift Tubes 4 Straight Airline Tubes 9 Filter Plate Connecters 4 Replaceable Filt-a-Carb Activated Carbon Media CartridgesMeasurements: Each Filter Plate Separately = 11.25” (W) x 11.25” (D) Filter Plates Together = 45” (W) x 11.25” (D) Each Lift Tube at Filter Plate Base = 13.25” – 16.5”Shop PENN-PLAX for All Your Pet’s Needs: PENN-PLAX is a manufacturer and distributor of top quality pet supplies, who specialize in creating excellent pet products for animals, both great and small.

Review: Best filter for the money - An under gravel is simply one of the best filters you can buy, dollar for dollar. This is because they are highly effective, simple, inexpensive, and last a long time. Here are some tips for how to use this filter correctly. 1. DO NOT OVER CLEAN YOUR GRAVEL. This is the most important thing. You should not clean your gravel much at all. Yes some brown stuff will accumulate. This brown stuff is not "fish poop". It is beneficial bacteria. If you remove this beneficial bacteria your filter will stop working and your fish may die. DO NOT OVER CLEAN YOUR GRAVEL. If you must clean your gravel, only clean 1/2 the tank at a time and give the cleaned side some time to regrow its bacteria before cleaning the other side. Otherwise only very lightly clean the top 1/2 inch of gravel. 2. You do not really need the carbon cartridges. If you want to support Penn-Plax, I guess you could keep buying them. 3. Use 1-3 inches of 1/8 inch aquarium gravel on top of the filter. Under gravel filters are so effective because they provide a lot of surface area for beneficial bacteria to grow on. The more gravel you have the more effective this filter will be. 4. Decide whether you want to use a power head or an air pump to move water through the filter. Power heads will greatly increase the effectiveness of the filter and provide cleaner water. If you plan on having a lot of fish in your tank, you should use power heads. The power heads should be rated at a gallons per hour that is 2-3x the gallons of the tank. If you use air pumps, they should be rated for the size of your aquarium. 5. Decide whether you want to join the under gravel plates or not. If you are using air pumps I would not join the plates. Simply put an air stone in each uplift tube for each plate. You do not need to buy multiple air pumps. Just buy a simple 'T' joint to split the output from the pump. If you are using power heads, I would join every two plates and use one power head per two plates. Some people are complaining that this filter killed their fish which is very unfortunate. The filter did not kill their fish. Incorrect use of the filter killed their fish. They probably cleaned out all the gravel and removed all the beneficial bacteria which caused the filter to stop working. Unless the filter has become so clogged that the water is no longer flowing through it, there is no need to clean the gravel or underneath the filter. If this does happen, I would suggest that the person is greatly overfeeding their fish! Some people are complaining that this filter "produces high nitrate." Producing nitrate is the point of all filters and shows that a filter is functioning properly! If your nitrate levels are too high for you to manage, you are putting too much food in the tank. A different filter is not going to fix this. There are only two ways to remove nitrate from an aquarium: change the water or grow plants. Really the plants are just incorporating the nitrate into their bodies, so you will have to remove some plants eventually too if you want to actually remove the nitrate. There is a reason many successful hobbyist have used under gravel filters for decades and I am very glad that Penn-Plax makes this product!
Review: Great filter - Works great!! Helps keep our aquarium cleaner

## Features

- NOTHING LIKE OLD SCHOOL: The Clear-Free Premium Under Gravel Filter is air driven and utilizes an Air Pump (not included) to cycle crystal clear water throughout your aquarium, while keeping a crisp and neat look inside. This means there’s less “moving parts,” making for simplistic and easy maintenance. This filter is suitable for most 40 – 55 gallon aquariums.
- BIOLOGICAL, CHEMICAL, AND PHYSICAL FILTRATION: As air is pushed through the Air Stones and rises through the Lift Tubes, water is gently suctioned through gravel and the filter plates, allowing both air and water to pass through the Filt-a-Carb Activated Carbon Cartridges. When water continues to be drawn through, anaerobic bacteria collects and colonizes within the gravel and filter plates.
- ALSO AERATES YOUR TANK: Since the Clear-Free Premium Under Gravel Filter is air driven through the use of Air Stones and an Air Pump (not included), it also aerates your tank. In essence, your aquarium is being filtered and aerated at the same time, though the same system. It’s a filter and bubbler in 1.
- ITEMS INCLUDED: The Clear-Free Premium Under Gravel Filter includes 4 Filter Plates, 4 Adjustable Lift Tubes, 4 Straight Airline Tubes, 9 Filter Plate Connecters, and 4 Replaceable Filt-a-Carb Activated Carbon Media Cartridges.
- MEASUREMENTS: Each Filter Plate Separately = 11.25” (W) x 11.25” (D) / Filter Plates Together = 45” (W) x 11.25” (D) / Each Lift Tube at Filter Plate Base = 13.25” – 16.5”

## Technical Specifications

| Specification | Value |
|---------------|-------|
| Customer Reviews | 4.4 out of 5 stars 8,183 Reviews |

## Images

![Penn-Plax Undergravel Aquarium Filter for 40-55 Gallon Tanks – Four 11.25” x 11.25” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks (CFU55) - Image 1](https://m.media-amazon.com/images/I/819cRGofPsL.jpg)

## Available Options

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

## Questions & Answers

**Q: Hello! i have a 55 gallon tank. how does this filter work? does it come with everything i need? and if there is a video on it please send it. thanks**
A: Thank you for your question. This filter has a plastic filter plate which lies under the gravel of the tank. This plate allows water to flow freely under the gravel. Water is drawn through the gravel and cleaned removing bateria and debris. In order for this air filter to work properly you will need an air pump as well as airline tubing. We like the Air Pod Pump B003DHYB52 and B0002563MW for air tubing. We don't have a video at this time but will have one soon.

**Q: Can i configure this to fit a container that is 12.5" x 12.5"? Can experts recommend something better if not?**
A: The 40/55 comes with four plates. Each plate has two tube attachments.  One plate would fill a 12.5".  Even if it were a little big you could score it (its plastic) and make it fit.

**Q: Is it 11.5' square as in the decription or 13" as in the picture?**
A: If you're getting it for a 55 gal aquarium the best I can tell you without tearing mine up out of my tank is that its perfect for the 55g , I've got them in my 10g , 39g bow front , 55g , and one in my 60g acrylic.

**Q: What size should i get gor a 36 gallon tank**
A: I have a 55 gallon tank and I used all the supplies flooring pieces, I think using this you may only require 3 of the flooring pieces possibly two if it’s a taller tank and not a show tank

## Customer Reviews

### ⭐⭐⭐⭐⭐ Best filter for the money
*by M***S on May 12, 2022*

An under gravel is simply one of the best filters you can buy, dollar for dollar. This is because they are highly effective, simple, inexpensive, and last a long time. Here are some tips for how to use this filter correctly. 1. DO NOT OVER CLEAN YOUR GRAVEL. This is the most important thing. You should not clean your gravel much at all. Yes some brown stuff will accumulate. This brown stuff is not "fish poop". It is beneficial bacteria. If you remove this beneficial bacteria your filter will stop working and your fish may die. DO NOT OVER CLEAN YOUR GRAVEL. If you must clean your gravel, only clean 1/2 the tank at a time and give the cleaned side some time to regrow its bacteria before cleaning the other side. Otherwise only very lightly clean the top 1/2 inch of gravel. 2. You do not really need the carbon cartridges. If you want to support Penn-Plax, I guess you could keep buying them. 3. Use 1-3 inches of 1/8 inch aquarium gravel on top of the filter. Under gravel filters are so effective because they provide a lot of surface area for beneficial bacteria to grow on. The more gravel you have the more effective this filter will be. 4. Decide whether you want to use a power head or an air pump to move water through the filter. Power heads will greatly increase the effectiveness of the filter and provide cleaner water. If you plan on having a lot of fish in your tank, you should use power heads. The power heads should be rated at a gallons per hour that is 2-3x the gallons of the tank. If you use air pumps, they should be rated for the size of your aquarium. 5. Decide whether you want to join the under gravel plates or not. If you are using air pumps I would not join the plates. Simply put an air stone in each uplift tube for each plate. You do not need to buy multiple air pumps. Just buy a simple 'T' joint to split the output from the pump. If you are using power heads, I would join every two plates and use one power head per two plates. Some people are complaining that this filter killed their fish which is very unfortunate. The filter did not kill their fish. Incorrect use of the filter killed their fish. They probably cleaned out all the gravel and removed all the beneficial bacteria which caused the filter to stop working. Unless the filter has become so clogged that the water is no longer flowing through it, there is no need to clean the gravel or underneath the filter. If this does happen, I would suggest that the person is greatly overfeeding their fish! Some people are complaining that this filter "produces high nitrate." Producing nitrate is the point of all filters and shows that a filter is functioning properly! If your nitrate levels are too high for you to manage, you are putting too much food in the tank. A different filter is not going to fix this. There are only two ways to remove nitrate from an aquarium: change the water or grow plants. Really the plants are just incorporating the nitrate into their bodies, so you will have to remove some plants eventually too if you want to actually remove the nitrate. There is a reason many successful hobbyist have used under gravel filters for decades and I am very glad that Penn-Plax makes this product!

### ⭐⭐⭐⭐⭐ Great filter
*by B***S on January 7, 2026*

Works great!! Helps keep our aquarium cleaner

### ⭐⭐⭐⭐ A bit noisy
*by H***M on August 11, 2025*

Not sure I would recommend this for an open rimless tank, might be ok with a tank that has a complete lid reason being it takes at least a 30-60gal. rated air pump to run all four air bubblers & then the bubbles coming out the top are constantly popping & its quite loud. Might not be an issue if the tank lid muffled the noise. I think if I run two small air pumps - one for each side running two air stones it might cut down on the noise level since the force of air will be reduced so less bubble force. Other than that product seems good quality.

## Frequently Bought Together

- Penn-Plax Undergravel Aquarium Filter for 40-55 Gallon Tanks – Four 11.25” x 11.25” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks (CFU55)
- AQUANEAT Aquarium Air Pump 300GPH, for up to 200 Gallon Fish Tank, Powerful Hydroponic Aerator Pump with Tubing, Air Stones, Valves
- Penn-Plax Standard Airline Tubing for Aquariums – Clear and Flexible – Resists Kinking – Safe for Freshwater and Saltwater Fish Tanks – 25 Feet

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*Product available on Desertcart Hungary*
*Store origin: HU*
*Last updated: 2026-01-31*