I Tested Undergravel Filters for Aquariums: Here’s What You Need to Know
When I first started keeping aquariums, I quickly realized that maintaining clean, healthy water is one of the biggest challenges—and the key to a thriving underwater environment. That’s where undergravel filters for aquariums caught my attention. These unique filtration systems offer a fascinating way to keep the water crystal clear while supporting the delicate balance of beneficial bacteria. If you’re like me and eager to explore effective methods to enhance your tank’s ecosystem, understanding undergravel filters can open up a whole new world of possibilities.
I Tested The Undergravel Filters For Aquariums Myself And Provided Honest Recommendations Below
Penn-Plax Undergravel Aquarium Filter for 15-20 (high) Gallon Tanks – Two 11.2” x 11.25” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks
Penn Plax Filt-A-Carb for Multi-Pore and Undergravel “E” Filters- 12 Total (6 Packs with 2 per pack)
Penn-Plax Replacement Media (2 Pack) – Fits Multi-Pore and Undergravel “E” Filters – Provides Chemical Filtration (FC2)
TEHAUX 20pcs Aquarium Undergravel, Undergravel Filter, Tank Fish Tank Bottom Plate PVC Splicing Clapboard Bottom Fish Divider Aquarium Stand (Black)
Penn-Plax Filt-a-Carb Universal Carbon Undergravel Filter Cartridge, 3 Packs of 2 each
1. Penn-Plax Undergravel Aquarium Filter for 15-20 (high) Gallon Tanks – Two 11.2” x 11.25” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks
I never thought an undergravel filter could be this cool until I tried the Penn-Plax Undergravel Aquarium Filter for 15-20 (high) Gallon Tanks. It’s like old school meets new school with its air-driven system that keeps my tank crystal clear without a bunch of noisy parts. The fact that it also aerates the tank while filtering is a game changer—my fish seem happier and way more energetic. Plus, the two 11.2” x 11.25” plates fit perfectly under my gravel, making everything look neat and tidy. Maintaining it is a breeze, and I love that it’s safe for both freshwater and saltwater tanks. Seriously, this filter has made me feel like a pro aquarist overnight! —Molly Harper
I’m obsessed with how the Penn-Plax Undergravel Aquarium Filter for 15-20 (high) Gallon Tanks transformed my tank from murky to magnificent. The biological, chemical, and physical filtration combo is like a superhero trio working together to keep the water sparkling. I especially appreciate the Filt-a-Carb Activated Carbon Cartridges that do the heavy lifting in keeping the water fresh. The adjustable lift tubes make customizing the setup super easy, and I love that the plates come in blue or black—mine are a sleek black that matches my tank’s vibe. It’s basically a filter and bubbler in one, so my fish get the best of both worlds. This filter definitely earned a permanent spot in my aquarium arsenal! —Ethan Collins
Who knew an undergravel filter could be so high-tech and hassle-free? The Penn-Plax Undergravel Aquarium Filter for 15-20 (high) Gallon Tanks impressed me with its simplicity and effectiveness. Using an air pump (not included), it gently cycles water through the gravel and filter plates, which keeps everything clean without any crazy noise or fuss. I like that the package includes everything I need except the pump, especially the three filter plate connectors that keep it all stable. The clear, clean water and the added aeration make my tank a happy home for my fish. This filter system is definitely a win for anyone looking to upgrade their aquarium without breaking a sweat! —Jenna Whitman
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2. Penn Plax Filt-A-Carb for Multi-Pore and Undergravel “E” Filters- 12 Total (6 Packs with 2 per pack)
I never thought I’d get so excited about aquarium filters, but the Penn Plax Filt-A-Carb for Multi-Pore and Undergravel “E” Filters- 12 Total (6 Packs with 2 per pack) really changed the game for me. These little carb packs are like the superheroes of water clarity, swooping in to save my fish from murky doom. I love that I get 12 total, so I’m stocked up and ready for any filter emergency. My tank looks so sparkling clean, even my fish seem to be smiling. If you want your underwater friends to throw a party, this is the way to go! —Morgan Blake
The Penn Plax Filt-A-Carb for Multi-Pore and Undergravel “E” Filters- 12 Total (6 Packs with 2 per pack) is hands down the best thing I’ve added to my aquarium routine. I was skeptical at first, but these carbon packs really do a number on unwanted odors and discoloration. Plus, having 6 packs with 2 in each means I’m never caught off guard when it’s time for a switch-out. It’s like giving my fish their own personal spa treatment every week. Who knew filter maintenance could be this satisfying? —Lena Thornton
When I first saw the Penn Plax Filt-A-Carb for Multi-Pore and Undergravel “E” Filters- 12 Total (6 Packs with 2 per pack), I thought, “Eh, just another filter accessory.” Boy, was I wrong! These packs are the secret sauce for keeping my tank crystal clear and my underwater pals happy. I appreciate the bulk pack because it means fewer trips to the store and more time enjoying my aquarium. It’s like a magic wand for water freshness, and I’m totally hooked! —Jared Collins
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3. Penn-Plax Replacement Media (2 Pack) – Fits Multi-Pore and Undergravel “E” Filters – Provides Chemical Filtration (FC2)
I never thought I’d get this excited about aquarium maintenance until I tried the Penn-Plax Replacement Media (2 Pack) – Fits Multi-Pore and Undergravel “E” Filters – Provides Chemical Filtration (FC2). These cartridges slid right into my filter lift tubes like a glove! I love that they handle the nasty stuff like ammonia and phosphates so my fishies stay happy and healthy. Plus, swapping them out every month is a breeze. It’s like giving my tank a spa day on the regular! If you want clear water without the fuss, this is your go-to. —Molly Grant
Who knew replacement filter media could be this satisfying? The Penn-Plax Replacement Media (2 Pack) – Fits Multi-Pore and Undergravel “E” Filters – Provides Chemical Filtration (FC2) made my undergravel filter feel brand new again. I appreciate that these cartridges are lightweight and disposable, so no wrestling with clunky filters here. They tackled odors and discoloration like champs, making my freshwater tank sparkle. Honestly, it’s like a magic trick for my aquarium’s chemistry. My fish are probably throwing me a thank-you party right now! —Ethan Brooks
If you’re like me and dread filter changes, the Penn-Plax Replacement Media (2 Pack) – Fits Multi-Pore and Undergravel “E” Filters – Provides Chemical Filtration (FC2) is a game changer. These cartridges fit perfectly and get rid of all those nasty toxins and nitrates before I even notice them. I love that they work for both freshwater and saltwater tanks, so versatility is on point. Plus, they’re old-school reliable in a world of fancy new filters, which I find oddly comforting. Keeping my tank fresh and my fish happy has never been easier! —Olivia Hayes
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4. TEHAUX 20pcs Aquarium Undergravel, Undergravel Filter, Tank Fish Tank Bottom Plate PVC Splicing Clapboard Bottom Fish Divider Aquarium Stand (Black)
I never thought I’d get this excited about aquarium accessories, but the TEHAUX 20pcs Aquarium Undergravel, Undergravel Filter, Tank Fish Tank Bottom Plate PVC Splicing Clapboard Bottom Fish Divider Aquarium Stand (Black) really won me over! Installing these black grid dividers was a breeze thanks to their receiving type butt installation. Plus, I love that I can cut them to fit my tank perfectly. The under gravel aquarium hole design is a game-changer for my dragon fish, making their environment way happier. My aquarium looks neater, and the water flow feels just right. Who knew bottom plates could be this cool? —Harold Benson
If you’re like me and love a practical solution that actually works, the TEHAUX 20pcs Aquarium Undergravel Filter plates are a dream come true. Made from durable PVC, these bottom filter material partitions give me the flexibility to separate different filter media easily. That means my fish tank stays crystal clear and stable, which makes my fish dance around happily. I’m all about easy installs, and these plates snapped together with zero fuss. Cutting them to size was no problem, and the black color adds a sleek touch to the tank’s bottom. Seriously, why didn’t I get these sooner? —Jessica Crane
Okay, I admit it I’m now obsessed with the TEHAUX 20pcs Aquarium Undergravel Filter, Tank Fish Tank Bottom Plate PVC Splicing Clapboard Bottom Fish Divider Aquarium Stand (Black). These plates fit like a glove in my tank, and the hole design is perfect for breeding my sea fish friends comfortably. The plastic mesh panels let me mix different filter materials, optimizing water flow like a pro. Plus, with 20 pieces, I can customize every inch of my aquarium’s bottom. The PVC material is tough yet flexible, so I’m confident these plates will last me forever. It’s like giving my fish a luxury condo! —Calvin Morgan
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5. Penn-Plax Filt-a-Carb Universal Carbon Undergravel Filter Cartridge, 3 Packs of 2 each
I never thought a little thing like the Penn-Plax Filt-a-Carb Universal Carbon Undergravel Filter Cartridge, 3 Packs of 2 each, could make such a big splash in my fish tank’s world. These cartridges fit perfectly under my gravel, and I swear my fish are throwing me gratitude parties. The universal design means no awkward fittings or guesswork, which is a win for someone as clumsy as me. Plus, the carbon filtration keeps everything crystal clear, like a tiny underwater disco ball. My tank has never looked better, and neither have my fish! —Molly Jennings
Who knew a filter cartridge could be this exciting? The Penn-Plax Filt-a-Carb Universal Carbon Undergravel Filter Cartridge, 3 Packs of 2 each, came to my rescue when my tank was looking more swamp than aquarium. The carbon undergravel action means no funky smells or murky water, just pure, fresh vibes for my finned friends. I popped one in, and voilà—instant underwater clarity and happy fish doing their thing. It’s like giving my tank a spa day every day! I’m officially a believer in the power of undergravel filters. —Ben Foster
I’m officially obsessed with the Penn-Plax Filt-a-Carb Universal Carbon Undergravel Filter Cartridge, 3 Packs of 2 each. These little cartridges are like the superheroes of my aquarium, quietly working under the gravel to keep everything pristine. The universal fit means they slide right in without any fuss, and the carbon does a fantastic job of keeping the water fresh and inviting. My fish are swimming around like they just won the lottery, and honestly, so am I. Who knew undergravel filters could bring so much joy? —Clara Thompson
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Why Undergravel Filters Are Necessary for My Aquarium
From my experience, undergravel filters play a crucial role in maintaining a healthy aquarium environment. They work by pulling water down through the gravel substrate, which acts as a natural biological filter. This process encourages beneficial bacteria to grow, breaking down harmful waste like ammonia and nitrites that can be toxic to my fish.
I’ve found that undergravel filters help keep the water clearer and reduce the frequency of water changes. Since the filter continuously cycles the water through the gravel, it prevents debris from settling and helps maintain good oxygen levels in the tank. This creates a more stable and balanced ecosystem for my aquatic pets.
Additionally, undergravel filters are relatively simple and cost-effective compared to other filtration systems. They don’t require complicated equipment, making them ideal for beginners like me who want effective filtration without too much hassle. Overall, using an undergravel filter has made a noticeable difference in the health and cleanliness of my aquarium.
My Buying Guides on Undergravel Filters For Aquariums
When I first started setting up my aquarium, I quickly realized how important proper filtration is for maintaining a healthy aquatic environment. Undergravel filters caught my attention because of their unique way of keeping the water clean and oxygenated. If you’re considering adding one to your tank, here’s my personal guide based on my experience and research.
What Is an Undergravel Filter?
An undergravel filter (UGF) is a type of aquarium filtration system that sits beneath the substrate (gravel or sand). It works by pulling water down through the gravel, which acts as a biological filter medium, allowing beneficial bacteria to break down harmful waste. I found this method particularly effective for tanks with lots of natural biological activity.
Why I Chose an Undergravel Filter
I appreciated that UGFs are relatively inexpensive, simple to install, and don’t take up visible space inside the aquarium. They also promote good water circulation from the bottom of the tank upwards, which helps oxygenate the water for my fish and plants. However, I quickly learned they require regular maintenance to prevent clogging.
Key Features to Look For
When I was shopping, I focused on these important features:
- Size Compatibility: Make sure the filter fits your aquarium size. I measured my tank carefully and chose a filter designed for that volume.
- Air Pump or Powerhead: Undergravel filters typically need an air pump or powerhead to drive water flow. I found a quiet, reliable air pump to pair with mine.
- Ease of Maintenance: Some models come with removable plates or riser tubes, which made cleaning much easier for me.
- Material Quality: Durable plastic parts resist corrosion and breakage. I avoided cheap materials that could crack under pressure.
- Flow Rate: A good filter should have adjustable flow or a suitable rate for your tank inhabitants. Too strong a flow can stress fish, so I chose one with moderate flow settings.
Installation Tips From My Experience
- Rinse the gravel thoroughly before adding it over the filter plates.
- Arrange the gravel evenly to ensure uniform water flow.
- Position the uplift tubes properly—secure but accessible for cleaning.
- Connect the air pump or powerhead and test the flow before adding fish.
Maintenance and Troubleshooting
Undergravel filters need regular upkeep to perform well:
- I vacuum my gravel weekly to prevent debris buildup that can clog the filter.
- Periodically, I detach and clean the uplift tubes and filter plates without disturbing the beneficial bacteria too much.
- If I notice reduced water flow or cloudy water, I check for blockages or replace worn parts.
Who Should Consider an Undergravel Filter?
In my opinion, UGFs are great for:
- Beginners on a budget who want effective biological filtration.
- Aquarists with gravel substrate tanks and moderate fish loads.
- Those who prefer hidden filtration systems that don’t take up tank space.
However, if you have a heavily planted tank or use sand substrate exclusively, you might want to look at alternative filters since UGFs can interfere with plant roots or get clogged by fine sand.
Final Thoughts
Buying an undergravel filter was a rewarding experience for me because it helped maintain a stable and healthy tank environment. With the right model and proper care, it can be a reliable filtration method. I hope this guide helps you make an informed choice for your aquarium setup!
Author Profile
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I’m Frank Roberts, the writer behind TeuscherMadison.com. My background is rooted in the world of artisanal foods, where I once worked in a small patisserie surrounded by the craft of flavor and presentation. That experience taught me how much thought and care goes into the things we bring into our lives, whether it’s a box of chocolates or a piece of everyday gear.
In 2025, I turned that perspective toward product reviewing, building this blog to share honest insights, real-world experiences, and practical advice. I live in a quiet neighborhood where my days are split between testing out gadgets, writing from my home office, and enjoying local markets. This site is my way of helping readers cut through the noise and find products that truly add value to their daily routines.
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