Under gravel filters are the quiet workhorses of aquarium filtration. Beneficial bacteria colonize your gravel substrate and naturally break down waste, keeping your water clean without visible equipment cluttering the tank.
They’re affordable, easy to set up, and they don’t take up valuable swimming space. But not all UGFs are created equal.
Here are 10 of the best, evaluated for tank size compatibility, filtration quality, and build durability.
This versatile UGF fits aquariums from 5 to 55 gallons and comes with jumbo 1-inch lift tubes, filt-a-carb cartridges, and crack-resistant plastic plates. It provides both biological and chemical filtration.
Quick Comparison Chart
| # | Under Gravel Filter | Our Rating | ||
|---|---|---|---|---|
| 1 |  |
Penn Plax Premium | ★★★★★ | Check Price |
| 2 |  |
Lee's 40/55 Premium | ★★★★★ | Check Price |
| 3 |  |
Aquarium Equip Circular Bar | ★★★★☆ | Check Price |
| 4 |  |
XMHF Aquarium UGF | ★★★★☆ | Check Price |
| 5 |  |
Aquarium Equip ISTA | ★★★★☆ | Check Price |
| 6 |  |
Uxcell 28-Piece | ★★★★☆ | Check Price |
| 7 |  |
Lee's 2½. Original | ★★★★☆ | Check Price |
| 8 |  |
Imagitarium UGF | ★★★★ | Check Price |
| 9 |  |
Lee's Fishbowl Filter | ★★★★ | Check Price |
| 10 |  |
Aquarium Equip 7.8x5.5 | ★★★★ | Check Price |
1. Penn Plax Premium — Best Overall
Penn Plax Premium UnderGravel Filter System
Suitable for aquariums from 5 to 55 gallons, this Penn Plax filter comes with jumbo 1-inch lift tubes, filt-a-carb cartridges, crack-resistant plastic plates, and high pore air stones.
Pros
- Comes with filt-a-carb cartridges for chemical filtration
- Jumbo 1-inch lift tubes provide excellent surface area
- Includes marble gravel so no separate purchase needed
- Easy to assemble with various size options
Cons
- Gravel may need rinsing before use
- Lift tubes may need trimming for shorter tanks
- Chemical filter cartridges need replacing every 6-8 weeks
The jumbo 1-inch lift tubes are fully adjustable and provide the best surface area for filtration. Penn Plax solves the common UGF problem of lacking chemical filtration by including 2 filt-a-carb cartridges that produce crystal clear water for 6-8 weeks.
The filter plates are completely crack-resistant plastic that can last years if installed properly. You also don’t need to buy gravel separately since it comes with marble gravel that’s clean and aesthetic.
It’s available in various price and size ranges, and the wide tank size compatibility makes it the best undergravel filter option on the market.
2. Lee’s 40/55 Premium — Best for Large Tanks
Lee's 40/55 Premium UnderGravel Filter
This undergravel filter features a multilayer plate design built with crack-resistant plastic. It fits a 48-inch tank with 55-60 gallon capacity and holds 70-80 pounds of gravel.
Pros
- Made of long-lasting crack-resistant plastic
- Comes with riser tubes and 4 carbon cartridges
- Supports both biological and chemical filtration
- Easy to assemble in under 15 minutes
Cons
- Only designed for large tanks
- Heavy gravel load can make cleaning difficult
- Riser tubes may need adjustment for tank height
The package ships with two bottom plastic plates, four clear plastic riser tubes, and gravel. The riser tubes can be fitted with powerheads, aerators, or canister filter inlets for strong biological filtration.
It holds about 70-80 pounds of gravel, making it the best water filter for large tanks and aquariums. Although it works for both saltwater and freshwater tanks, aquarists prefer it for large saltwater tanks because of the added plate strength.
It comes with an instruction manual and can be easily put together within 15 minutes, making it the top choice among beginner fish parents everywhere.
3. Aquarium Equip Circular Bar — Best Hidden Filter
Aquarium Equip UnderGravel Circular Bar
This truly hidden undergravel filter works in tanks up to 55 gallons. Its circular tubing system improves water temperature regulation and provides more surface area for faster filtration.
Pros
- Completely invisible from outside the aquarium
- Circular tubing improves temperature regulation
- Works with both sand and coarse gravel substrates
- Compatible with powerhead, airhead, sponge filter, and rain bar
Cons
- May require additional pump purchase
- Circular design limits tank shape compatibility
- No chemical filtration included
If you want a truly hidden undergravel filter that adds to the natural aesthetics of your aquarium, this is the perfect solution. Aquarists have been using it in both seawater and freshwater tanks because it maintains crystal clear water.
The circular tubing system keeps water constantly circulating through the tubes and the tank, improving temperature regulation. One of the rare benefits this filter offers is the presence of more surface area, making filtration less time-consuming and more efficient.
It comes with easy-to-assemble instructions making it user-friendly, especially for beginners.
4. XMHF Aquarium UGF — Best Customizable
XMHF Aquarium UnderGravel Water Filter
The XMHF filter consists of 28 small pieces that form a 7-layer filter board. This customizable design provides a size range from 5 to 90 gallons and supports double filtration.
Pros
- Compact, attractive layout with 28 modular pieces
- Vast size range from 5 to 90 gallons
- Double filtration keeps water extra clear
- Crack-resistant plastic is easy to clean
Cons
- No chemical filter included
- Assembly takes longer with more pieces
- Air pump sold separately
The filter board consists of 7 layers made by the assembly of 28 small pieces, making it capable of double filtration. Because assembly involves connecting various parts, it can be configured in many different ways to fit tanks from 5 to 90 gallons.
The package arrives with 28 UGF board pieces, uprise tubes, an air hose line, and an air stone. It can be used with a powerhead, air pump, or attached to the inlet of a canister filter.
It doesn’t come with a chemical filter, so it works best as a secondary filtration option alongside your primary chemical filter. For carbon block chemical filtration media, see our dedicated guide.
5. Aquarium Equip ISTA — Best for Small Tanks
Aquarium Equip ISTA UnderGravel Filter
The ISTA filter has two 12-inch durable plastic plates with adjustable uprise tubes. At 11.8 x 5.9 inches, it's best suited for small aquariums with 5 to 5.5 gallon capacity.
Pros
- Very affordable for small tank owners
- Adjustable uprise tube fits different tank heights
- Very quiet operation for home environments
- Works in both freshwater and saltwater
Cons
- Only works with coarse gravel substrate
- No chemical filtration support
- Limited to very small aquariums
The length of the uprise tube can be adjusted according to the height of your fish tank. The tube works with a powerhead, air pump, filter pump, or even hang-on-back style filters for better temperature regulation.
The gravel bed on top of the filter provides an excellent multiplying site for good bacteria. The boosted surface area helps circulate water under the gravel layer for quick filtration.
It’s a very affordable and efficient option that works great in both freshwater and saltwater environments.
6. Uxcell 28-Piece — Best Modular Design
Uxcell 28-Piece Plastic UnderGravel Filter
This Uxcell UGF comes with a petite, tightly packed framework. The 28-piece modular design creates a 7-layer filter capable of double filtration across a 5-90 gallon size range.
Pros
- Beautiful design with adjustable size options
- High-quality crack-resistant plastic
- Ideal as secondary filtration system
- Parts can be taken apart quickly for cleaning
Cons
- No chemical filter included
- Many pieces can be confusing to assemble
- Air pump must be purchased separately
The filter plates consist of 7 layers made by the assembly of 28 small pieces, making it capable of double filtration. Because assembly involves connecting various parts, it can be put together in many different shapes to fit tanks from 5 to 90 gallons.
The product ships with 28 UGF board pieces, an uprise tube, an air hose line, and an air stone for custom assembly based on your tank size.
It doesn’t come with a chemical filter, making it a perfect choice if you’re already using chemical filtration as your primary option.
7. Lee’s 2½. Original — Best Compact
Lee's 2½. Original UnderGravel Filter
This compact undergravel filter fits a 12-inch tank with up to 5 gallon water capacity. It comes with two plastic plates, two riser tubes, and four active carbon cartridges.
Pros
- Made of long-lasting crack-resistant plastic
- Comes with riser tubes and 4 carbon cartridges
- Provides both biological and chemical filtration
- Easy to assemble in under 15 minutes
Cons
- Only suitable for very small tanks
- Limited gravel capacity of 10-15 pounds
- Riser tubes may need trimming
The package ships with two bottom plastic plates and two clear plastic riser tubes. The riser tubes can be fitted with powerheads, aerators, or canister filter inlets for strong mechanical filtration.
It can be used in tanks with fish of all ages. Fish keepers prefer to use it in small freshwater tanks, though it works for saltwater too.
It comes with four active carbon cartridges for chemical filtration and includes an instruction manual for easy assembly in under 15 minutes.
8. Imagitarium UGF — Best Chemical Filtration
Imagitarium UnderGravel Water Filter
The Imagitarium filter works with or without carbon cartridges and fits both ammonia and carbon replacement filters. It includes 2 plastic plates, 2 uprise tubes, and 2 carbon cartridges.
Pros
- Works with both ammonia and carbon replacement filters
- Complete package with plates, tubes, and cartridges
- Made with high-quality crack-resistant plastic
- Functions in both freshwater and saltwater
Cons
- Limited to approximately 10 gallon tanks
- Carbon cartridges need regular replacement
- Assembly instructions could be clearer
What sets this filter apart is that it works with or without carbon cartridges. You can choose whether you want chemical filtration as the primary option depending on your circumstances.
The uprise tubes can be fitted with powerheads, aerators, or canister filter inlets simultaneously depending on your tank’s needs. One special quality is its ability to fit with more than one type of chemical filter, including both ammonia and carbon replacement filters.
This versatility makes it one of the best chemical undergravel filters available on the market today.
9. Lee’s Fishbowl Filter — Best for Fishbowls
Lee's Pet Products Fishbowl Filter
This rare fishbowl undergravel filter comes with carbon cartridges and a beautiful green artificial plant. It provides quiet, noise-canceling operation perfect for the calm ecosystem of a fishbowl.
Pros
- Designed especially for small fishbowls
- Ships with carbon cartridges and decorative plant
- Quiet, noise-canceling operation
- Easy to assemble in 10-15 minutes
Cons
- Only fits small fishbowl sizes
- Artificial plant may not suit all aesthetics
- Limited filtration capacity
Undergravel filters that fit fishbowls are very difficult to find because of their smaller sizes and lesser demand. A calm and peaceful ecosystem is a special need in fishbowls, and this noise-canceling quiet filter is the best option for achieving that atmosphere.
The package includes two carbon cartridges, one round high-quality filter plate, one decorative green plant, and one clear plastic uprise tube. The gravel on top of the filter provides an easy place for beneficial bacteria to lodge.
It can be assembled and used within 10-15 minutes using the included instructions.
10. Aquarium Equip 7.8x5.5 — Best Budget
Aquarium Equip UnderGravel Filter 7.8x5.5
This lightweight plastic filter is perfect for small aquariums at 7.8 x 5.5 inches with up to 5 gallon capacity. It works with coarse gravel or air stones and suits fish of every age.
Pros
- Good quality plastic at an affordable price
- Easy to assemble in under 10 minutes
- Low maintenance with no frequent cleaning needed
- Suitable for fish of every age and size
Cons
- Only works for very small tanks
- No chemical filtration included
- Limited to coarse gravel substrate
It’s suitable for both freshwater and saltwater tanks, making it an excellent choice for beginner pet parents using small tanks. It comes with an uprise tube that can be fitted with a powerhead, air pump, or canister.
It works best with coarse gravel, air stones, or a mixture of both to keep your fish tank crystal clear and bubbly. If you’re looking for a low-maintenance, easy-to-run system, this is the filter for you.
The package comes with easy-to-install instructions that let you’ve it fully functional within 10 minutes, making it the best budget solution for a small aquarium. For larger pond setups, different filtration systems are needed.
Frequently Asked Questions
Picture a perforated plate that sits under your aquarium gravel. Water gets pulled down through the gravel by a pump, and beneficial bacteria that colonize the gravel do the actual filtering. They break down fish waste and keep the water clean naturally.
They're great for fish tanks. The biological filtration is completely natural since beneficial bacteria colonize the gravel and do all the work. They're affordable, easy to set up, and don't take up visible space in your tank.
Vacuum the gravel every 1-2 weeks during your regular water changes. The plates themselves almost never need attention. Just don't deep-clean all the gravel at once because you'll wipe out the bacteria colonies that are doing the actual filtering.
Generally, no. Fine sand clogs the plate slots and chokes water flow. Stick with coarse gravel for most models. That said, a few designs like the Aquarium Equip Circular Bar are built to handle both sand and gravel.
Final Thoughts
Under gravel filters are one of those products where simplicity is the whole point. They work quietly in the background, letting nature handle the filtration.
The key is getting the right size. Your plates need to fit the bottom of your tank, so measure first. Also decide whether you want biological filtration alone or if you'd like chemical filtration too.
From large aquariums to small fishbowls, there's an option here that fits. The Penn Plax Premium covers the widest range and includes everything you need out of the box.
The Penn Plax Premium is our top pick for the best under gravel water filter thanks to its versatile 5-55 gallon range, included chemical filtration cartridges, and marble gravel. For large tanks, the Lee's 40/55 Premium handles up to 80 pounds of gravel, while the Lee's Fishbowl Filter is perfect for small fishbowl setups.
