Penn-Plax Premium Underground Aquarium Filter, 55-gal

$29.99 (-30%) Chewy Price
$42.99 List Price
Promo, New Customers Only: Spend $49+, Get $20 eGift Card + Free Shipping with code: WELCOME

In Stock
FREE 1-3 day delivery on first-time orders over $35
Free 365-day returns

About This Item

Details

  • This air-driven filter utilizes an air pump and air stones to cycle water throughout your aquarium, promoting a crisp, clean tank.
  • Designed to provide biological, chemical, and physical filtration in one easy system.
  • The thoughtful design also aerates your tank for added convenience.
  • Includes 2 filter plates, 2 adjustable lift tubes, 2 straight airline tubes, 3 filter plate connectors, and 2 replaceable Filt-a-Carb Activated Carbon Media Cartridges.
  • An air pump and air stones are required for use (each sold separately).

Instructions

Size

Learn More About Penn-Plax From Our Team of Experts

Compare Similar Items

Penn-Plax
Premium Underground Aquarium Filter, 55-gal
Penn-Plax
Premium Underground Aquarium Filter, 55-gal
$29.99 Chewy Price
($0.55/gl)
Rated 4.1 out of 5 stars
94Reviews
Made In           
China
United States
China
United States
United States
United States
China
China
United States
Fish Type           
Cichlid, Goldfish, Marine Fish, Tropical Freshwater
Marine Fish, Tropical Freshwater
Betta, Cichlid, Goldfish, Tropical Freshwater
Betta, Cichlid, Goldfish, Marine Fish, Tropical Freshwater
Marine Fish, Tropical Freshwater
Marine Fish, Tropical Freshwater
Betta, Bottom Feeder, Cichlid, Discus, Goldfish, Marine Fish, Marine Invertebrate, Tropical Freshwater
Betta, Bottom Feeder, Cichlid, Discus, Goldfish, Marine Fish, Marine Invertebrate, Tropical Freshwater
Betta, Bottom Feeder, Cichlid, Discus, Goldfish, Marine Fish, Marine Invertebrate, Tropical Freshwater
Tropical Freshwater
Marine Fish, Tropical Freshwater
Betta, Cichlid, Goldfish, Marine Fish, Tropical Freshwater
Aquarium Type           
Saltwater, Freshwater
Saltwater
Saltwater, Freshwater
Saltwater, Freshwater
Saltwater, Freshwater
Saltwater, Freshwater
Pond
Saltwater, Freshwater
Saltwater, Freshwater
Saltwater, Freshwater
Saltwater, Freshwater
Saltwater, Freshwater
Tank Size           
41 to 55 Gallons
21 to 30 Gallons
11 to 20 Gallons
41 to 55 Gallons, 31 to 40 Gallons
31 to 40 Gallons
41 to 55 Gallons, 56 to 75 Gallons
11 to 20 Gallons
11 to 20 Gallons
21 to 30 Gallons
21 to 30 Gallons
6 to 10 Gallons

Questions & Answers

21 Customer Questions


ware can i get replacement fillters

Answer by ChewyJan 18, 2021
At this time, we do not carry the filters however, the Penn-Plax Filt-a-Carb Carbon Undergravel Filter Cartridges are available directly through the manufacturer.

What exactly comes in this package?

Answer by ChewyDec 14, 2021
The Under Gravel filter will have the plates, lift tubes, carbon cartridges, and air stones. It does not come with an air pump and air tubing.

Can i use this filter in conjunction with canister filter and water circulation pump?

Answer by ChewyJul 10, 2019
This undergravel filter may be used along with a canister filter. Before using, ensure the intake tube is not near anything that is causing air bubbles. The canister filter will pull in the bubbles along with water and air will build up inside the canister.

Do the tubes need to be completely submerged under water for this filter to work ?

Answer by ChewyOct 02, 2019
The entire filter, including the cartridges and tubes should be fully submerged under water, in order to operate properly. Nothing should be sticking out above the surface of the aquarium.

4.1
Rated 4.1 out of 5 stars
94 Ratings

57 Customer Reviews



Rated 4 out of 5 stars
By Scherry on Oct 15, 2025

Works ok with modifications.

Works ok with modifications. The base fits on the bottom of my 10 gallon tank fine but I had to modify the tubes to go down in the water. They were above the water

Works ok with modifications. The base fits on the bottom of my 10 gallon tank fine but I had to modify the tubes to go down in the water. They were above the water even after I pushed them all the way down. I cut off about 2" on each tube. I plan on starting a quarantine tank and will use this one in that tank and get another better one for my main tank.


Rated 1 out of 5 stars
By Sue on Oct 12, 2025

Undergravel filter

It came broken, but I kept for parts.

It came broken, but I kept for parts.


Rated 5 out of 5 stars
By Sue on Aug 8, 2025

Working great

Fish tank clear & with air pump connected very quiet.

Fish tank clear & with air pump connected very quiet.


Rated 5 out of 5 stars
By Anne on Jul 10, 2025

Great product

Well constructed and perfect solution for our new aquarium.

Well constructed and perfect solution for our new aquarium.


Rated 3 out of 5 stars
By Andrew on Feb 18, 2025

Flimsy

The plastic of the bottom plates is soft and flimsy. I wanted to add some rockwork to the tank and am concerned it may crush or break it. I was trying to save

The plastic of the bottom plates is soft and flimsy. I wanted to add some rockwork to the tank and am concerned it may crush or break it. I was trying to save money, but next time I will try a different brand.


Rated 5 out of 5 stars
By Micheal on Jun 23, 2025

Perfect fit for a 60 gallon tall

Tu to customer service for double checking measurements

Tu to customer service for double checking measurements


Rated 5 out of 5 stars
By Jacqueline on Jan 5, 2025

Wouldn't be without this!

Old school or not, undergravel works so well, I think I'll always use them! Have tried just hang on back type, fancy bookbag types and sponge filters, and combos

Old school or not, undergravel works so well, I think I'll always use them! Have tried just hang on back type, fancy bookbag types and sponge filters, and combos of all, but this is the base filtration for all my tanks. Tried and true!


Rated 5 out of 5 stars
By Phillip on Jun 6, 2025

Sold at a terrific price.

A great and very affordable undergravel filter.

A great and very affordable undergravel filter.


Rated 5 out of 5 stars
By Robert on Jan 12, 2025

Have one in every tank

I’ve used undergravel filters for every tank I’ve set up over 30 years now. The undergravel filter is where the majority of the good bacteria is for a healthy t

I’ve used undergravel filters for every tank I’ve set up over 30 years now. The undergravel filter is where the majority of the good bacteria is for a healthy tank


Rated 5 out of 5 stars
By Gerard on Apr 29, 2025

Aquarium under gravel filter

Works great

Works great