Undergravel Filters

Undergravel filters can be an efficient and economical choice of filter depending on the aquarium size and fish that you are keeping. They were once found in the majority of aquariums, but have slowly fallen in popularity. They are, however, still a viable choice in many circumstances.

How Does an Undergravel Filter Work?

Undergravel filters, unsurprisingly, use gravel to aid in the filtration process. When the gravel is of appropriate height (ideally at least 2 inches) is can act as an efficient filtration medium.

A layer of “good bacteria” forms on the gravel. Water is then drawn through the gravel, and is mechancially and biologically filtered in the process. The filtration cycle is then completed as the water is returned from the filter back into the aquarium.

Are Undergravel Filters Outdated?

Undergravel filters have fallen in popularity in recent times, replaced by more complex (and more expensive options). They can be noisy at times, but are robust and cheap enough that they are still a common choice today.

Today, undergravel filters are most commonly used:

  1. In smaller fish tanks
  2. As a secondary filter in larger tanks. In this way it is also used to add additional biological filtering (complementing more advanced filters that offer biological, mechanical and chemical filtering).

Undergravel Filter Setup

Undergravel filter setup is a simple process:

  1. First ensure that you have (or buy) an undergravel filter that is appropriate for the size of your tank (i.e. the amount of water that it holds).
  2. Ensure that the tank, tubes, piping and filter are clean and free from dust before beginning. Rinse with warm, clean water if necessary but do not use soap and similar products.
  3. Carefully connect the bubbler casing to the filtration plate, being careful not to use too much force.
  4. Connect the tubing to the bubbler
  5. Insert the bubbler into the casing tube.
  6. Attached the loose end of the tubing to the air pump.
  7. Hide the air pump on a flat surface near the fish tank
  8. Pick up the filtration baseplate and place it at the bottom of your fish tank
  9. Place approx. 2 inches of gravel on top of the baseplate.
  10. Fill the fish tank with water, ensuring it has the appropriate salinity and pH for the fish that you intend to house in your aquarium.
  11. Connect your air pump to a power source and also attach your water heater (if using one).

You should start to see bubbles appearing within a few seconds, indicating that your filter is working as desired.

Lee’s Original Undergravel Filter Reviews

Lee’s Aquarium & Pet Products was founded in 1975. To this day it is family owned and operated, and employs approximately 50 employees. Headquartered in San Marcos, California, approximately, 90% of Lee’s products are made in the USA, at their San Marcos facility. By manufacturing their own products, Lee’s consistently maintains product quality.

Lee’s Economy Undergravel Filters

Lee’s 5-1/2 Economy Undergravel Filter, 1 Plate, 8-Inch by 16-Inch

Lee's 5-1/2 Economy Undergravel FilterA Little Bit Fishy Score: 4/5
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Lee’s 10 Economy Undergravel Filter, 1 Plate – 10 x 20-Inches

Lee's 10 Economy Undergravel FilterA Little Bit Fishy Score: 4/5
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Lee’s 10 economy undergravel filter has a single filtration plate. The plate measures 20 inches by 10 inches and so is perfect for 10 gallon fish tanks. It is also the correct size for 16 and 20 gallon (tall) aquariums. This filter type is the most economical of Lee’s three undergravel filter styles. The plate is made of semi-flexible, break-resistant plastic.

Lee’s 15/20 Economy Undergravel Filter, 1 Plate, 12-Inch by 24-Inch

Lee's 15/20 Economy Undergravel FilterA Little Bit Fishy Score: 4.5/5
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Lee’s 15/20 economy undergravel filter has a single filtration plate. The plate measures 24 inches by 12 inches and so is perfect for 15 gallon tanks and standard shaped 20 gallon aquariums. It is also the correct size for 16 and 20 gallon (tall) aquariums. This filter type is the most economical of Lee’s three undergravel filter styles. The plate is made of semi-flexible, break-resistant plastic.

Lee’s 20/29 Economy Undergravel Filter, 1 Plate, 12-Inch by 30-Inch

Lee's 20L/29 Economy Undergravel FilterA Little Bit Fishy Score: 4.5/5
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Lee’s 20/29 economy undergravel filter has a single filtration plate. The plate measures 30 inches by 12 inches and so is perfect for 20 gallon (long) tanks and 29 gallon fish tanks. This filter type is the most economical of Lee’s three undergravel filter styles. The plate is made of semi-flexible, break-resistant plastic.

Lee’s 30 Economy Undergravel Filter, 1 Plate, 12-Inch by 36-Inch

Lee's 30 Economy Undergravel FilterA Little Bit Fishy Score: 4/5
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Lee’s 30 economy undergravel filter has a single filtration plate. The plate measures 36 inches by 12 inches and so is perfect for 30 gallon aquariums. This filter type is the most economical of Lee’s three undergravel filter styles. The plate is made of semi-flexible, break-resistant plastic.

Lee’s 40/55 Economy Undergravel Filter, 2 Plates, 12-Inch by 48-Inch

Lee's 40/55 Economy Undergravel FilterA Little Bit Fishy Score: 4.5/5
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Lee’s 40/55 economy undergravel filter has 2 filter plates. These make up a total area of 48 inches by 12 inches. It is therefore perfect for either 40 gallon (long) tanks or 55 gallon tanks. This filter type is the most economical of Lee’s three undergravel filter styles. The plate is made of semi-flexible, break-resistant plastic.

Lee’s Premium Undergravel Filters

Lee’s 20L/29 Premium Undergravel Filter, 12-Inch by 30-Inch

Lee's 20L/29 Premium Undergravel FilterA Little Bit Fishy Score: 4.5/5
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Lee’s 20/29 premium undergravel filter measures 36 inches by 12 inches and so is perfect for 20 gallon (long) and 29 gallon aquariums. These plates are more robust than the economy version and are made from special quality plastic which resists splitting and cracking. As such, they are often preferred by those wishing to have saltwater aquariums.

Lee’s 40/55 Premium Undergravel Filter, 12-Inch by 48-Inch

Lee's 40/55 Premium Undergravel FilterA Little Bit Fishy Score: 4/5
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Lee’s 40/55 premium undergravel filter measures 48 inches by 12 inches and so is perfect for 20 gallon (long) fish tanks. It can also be used for 55 gallon tanks. These plates are more robust than the economy version and are made from special quality plastic which resists splitting and cracking. As such, they are often preferred by those wishing to have saltwater aquariums.

Lee’s 50/65 Premium Undergravel Filter, 18-Inch by 36-Inch

Lee's 50/65 Premium Undergravel FilterA Little Bit Fishy Score: 4.5/5
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Lee’s 40/55 premium undergravel filter measures 36 inches by 18 inches and so is perfect for both 50 gallon and 65 gallon fish tanks. These plates are more robust than the economy version and are made from special quality plastic which resists splitting and cracking. As such, they are often preferred by those wishing to have saltwater aquariums.

Lee’s 70/90 Premium Undrgravel Filter 18-Inch by 48-Inch

Lee's 70/90 Premium Undergravel FilterA Little Bit Fishy Score: 4.5/5
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Lee’s 70/90 premium undergravel filter measures 48 inches by 18 inches and so is perfect for both 70 gallon and 90 gallon fish tanks. These plates are more robust than the economy version and are made from special quality plastic which resists splitting and cracking. As such, they are often preferred by those wishing to have saltwater aquariums.

Lee’s 125/135 Premium Undergravel Filter, 18-Inch by 72-Inch

Lee's 125/135 Premium Undergravel FilterA Little Bit Fishy Score: 4.5/5
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Lee’s 125/135 premium undergravel filter measures 72 inches by 18 inches and so is perfect for both 125 gallon and 135 gallon fish tanks. These plates are more robust than the economy version and are made from special quality plastic which resists splitting and cracking. As such, they are often preferred by those wishing to have saltwater aquariums.

Penn Plax Premium UnderGravel Filter System Reviews

Penn-Plax was formed in 1956 and has been assisting pet owners ever since. They produce a wide range of pet products for distribution around the world. They are well known for their premium undergravel filter systems. Here we review the various options offered and what aquariums they are suitable for. ​​

Penn Plax Premium Under Gravel Filter System – for 10 Gallon Fish Tanks & Aquariums

Penn Plax Premium Under Gravel Filter System - for 10 Gallon Fish TanksA Little Bit Fishy Score: 4.5/5
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Penn Plax’s premium undergravel filter system for 10 gallon fish tanks is designed for 20 inch by 10 inch tanks. It includes filter plates, air stones, adjustable lift tubes and filter cartridges. The filtration system provides chemical filtration in addition to the standard biological filtration.

Penn Plax Premium Under Gravel Filter System – for 20 Gallon Fish Tanks & Aquariums

Penn Plax Premium Under Gravel Filter System - for 20 Gallon Fish TanksA Little Bit Fishy Score: 4.5/5
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Penn Plax’s premium undergravel filter system for 20 gallon fish tanks is designed for 24 inch by 12 inch tanks. It includes filter plates, air stones, adjustable lift tubes and filter cartridges. The filtration system provides chemical filtration in addition to the standard biological filtration.

Penn Plax Premium Under Gravel Filter System – for 29 Gallon Fish Tanks & Aquariums

Penn Plax Premium Under Gravel Filter System - for 29 Gallon Fish TanksA Little Bit Fishy Score: 4.5/5
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Penn Plax’s premium undergravel filter system for 29 gallon fish tanks is designed for 30 inch by 12 inch tanks. It is therefore also suitable for 20 gallon (long) tanks). It includes filter plates, air stones, adjustable lift tubes and filter cartridges. The filtration system provides chemical filtration in addition to the standard biological filtration.

Penn Plax Premium Under Gravel Filter System – for 40-55 Gallon Fish Tanks & Aquariums

Penn Plax Premium Under Gravel Filter System - for 40-55 Gallon Fish TanksA Little Bit Fishy Score 4.5/5
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Penn Plax’s premium undergravel filter system for 40 gallon (long) fish tanks is designed for 48 inch by 12 inch tanks. It is therefore also suitable for 55 gallon tanks. It includes filter plates, air stones, adjustable lift tubes and filter cartridges. The filtration system provides chemical filtration in addition to the standard biological filtration.

Undergravel Filters – Other Options

For some tanks undergravel filters are perfect. However, if you would like to supplement your undergravel filter, it could be worth considering an Aqueon filter and perhaps even a hang on back protein skimmer.

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