How Much Substrate Does My Aquarium Need?

Who would have thought it would be so difficult to find out how much substrate you need for your aquarium? I have to be honest, when I wanted to add Fluval Stratum to my 150-gallon aquarium, I couldn’t find any decent articles telling me how much I would need to purchase.

To solve the problem of how much substrate you will need for your aquarium, I have written the following article, looking at all the most popular aquarium substrates, and then creating a table for each substrate, letting you know how much you will need for your tank based on a 1” layer, a 2” layer or a 3” layer.



How Do I Decide How Much Substrate My Aquarium Needs?

When you search the web for ‘how much aquarium substrate do I need?’, you will often see people quoting lbs per gallon. This is not a great way to work out how much substrate you will need.

The volume of the aquarium has no bearing on the footprint of the aquarium. My 5’ long 150 gallon needs a lot more substrate than a 150 gallon 6’ tall cylinder aquarium.

To work out how much substrate you would need, I built myself an aquarium that was 12” by 12” (30cm x 30cm). I then added a 1” layer of each substrate individually and weighed it. This process gave me an equation of lbs per square foot, per inch deep of substrate. I used this equation to populate each of the tables below.

For each of the substrates, I will add a little information. If you are looking for some detailed information about any of the substrates, follow the link below each to our ‘Product Guides’ page.

What Substrates Are Available For Aquariums

The list below contains some of the most popular substrates available. There are of course many others on the market, but in my experience, these are the most frequently used.

  • Gravel
  • Pea Shingle
  • Sand
  • Fluval Stratum
  • Caribsea Eco-Complete
  • Seachem Flourite or Flourite Black


How Much Aquarium Gravel Do I Need?

Aquarium gravel has been used as a substrate for decades. Typically, aquarium gravel is small with grains measuring between 3mm and 6mm. Gravel comes in a variety of colors and a natural finish. Aquarium gravel is great for growing plants.

For a 1” (2.5cm) layer of gravel, you need approximately 7lbs (3.2kg) of gravel per square foot of aquarium footprint. This means, for a 12” x 24” (30cm x 60cm) aquarium, you will need roughly 14lbs (6.4kg) of gravel per inch of substrate depth.

Use the table below to work out how much gravel you need for your aquarium.

Aquarium VolumeAquarium Size (L x W x H inches)1″ Layer2″ Layer3″ Layer
20 Gallon High24 x 12 x 1612lbs (5.5kg)24lbs (10.9kg)36lbs (16.3kg)
20 Gallon Long30 x 12 x 1215lbs (6.8kg)30lbs (13.6kg)45lbs (20.4kg)
25 Gallon24 x 12 x 2012lbs (5.5kg)24lbs (10.9kg)36lbs (16.4kg)
29 Gallon30 x 12 x 1815lbs (6.8kg)30lbs (13.6kg)45lbs (20.4kg)
30 Gallon Breeder36 x 18 x 1227lbs (12.2kg)54lbs (24.5kg)81lbs (36.7kg)
40 Gallon Long48 x 12 x 1624lbs (10.9kg)48lbs (21.8kg)72lbs (32.7kg)
40 Gallon Breeder36 x 18 x 1627lbs (12.2kg)54lbs (24.5kg)81lbs (36.7kg)
50 Gallon36 x 18 x 1927lbs (12.2kg)54lbs (24.5kg)81lbs (36.7kg)
55 Gallon48 x 13 x 2130lbs (13.6kg)60lbs (27.2kg)90lbs (40.8kg)
65 Gallon36 x 18 x 2427lbs (12.2kg)54lbs (24.5kg)81lbs (36.7kg)
75 Gallon48 x 18 x 2136lbs (16.3kg)72lbs (32.6kg)108lbs (49.9kg)
90 Gallon48 x 18 x 2436lbs (16.3kg)72lbs (32.6kg)108lbs (49.9kg)
125 Gallon72 x 18 x 2154lbs (24.5kg)108lbs (49.9kg)162lbs (73.5kg)
150 Gallon72 x 18 x 2854lbs (24.5kg)108lbs (49.9kg)162lbs (73.5kg)
180 Gallon72 x 24 x 2572lbs (32.6kg)144lbs (65.2kg)216lbs (97.8kg)
Sale
Spectrastone Shallow Creek Regular for Freshwater Aquariums, 5-Pound Bag
1,993 Reviews
Spectrastone Shallow Creek Regular for Freshwater Aquariums, 5-Pound Bag
  • Will not affect PH
  • Safe for use in freshwater aquariums
  • Non-Toxic coating

Last update on 2022-11-23 / Affiliate links / Images from Amazon Product Advertising API

How Much Pea Shingle Do I Need For My Aquarium?

Pea shingle is a slightly larger version of normal aquarium gravel which typically measures around 6mm to 10mm. Pea shingle is normally only available in a natural color and is typically cheaper than aquarium gravel.

Pea shingle is often used for larger goldfish or for tanks with big cichlids.

For a 1” (2.5cm) deep layer of pea shingle, you will need roughly 9lbs (4.25kg) of pea shingle per square foot of aquarium footprint. This means, for a 12” x 24” (30cm x 60cm) fish tank, you will need about 18lbs (8.5kg) of pea shingle for every 1” (2.5cm) of substrate depth.



Use the table below to find out how much pea shingle you will need for your aquarium.

Aquarium VolumeAquarium Size (L x W x H inches)1″ Layer2″ Layer3″ Layer
20 Gallon High24 x 12 x 1618.6lbs (8.4kg)37.2lbs (16.9kg)55.8lbs (25.3kg)
20 Gallon Long30 x 12 x 1223.2lbs (10.5kg)46.5lbs (21.0kg)69.7lbs (31.5kg)
25 Gallon24 x 12 x 2018.6lbs (8.4kg)37.2lbs (16.9kg)55.8lbs (25.3kg)
29 Gallon30 x 12 x 1823.2lbs (10.5kg)46.5lbs (21.0kg)69.7lbs (31.5kg)
30 Gallon Breeder36 x 18 x 1241.8lbs (19.0kg)83.7lbs (38.0kg)125lbs (57.0kg)
40 Gallon Long48 x 12 x 1637.2lbs (16.9kg)74.4lbs (33.8kg111lbs (50.7kg)
40 Gallon Breeder36 x 18 x 1641.8lbs (19.0kg)83.7lbs (38.0kg)125lbs (57.0kg)
50 Gallon36 x 18 x 1941.8lbs (19.0kg)83.7lbs (38.0kg)125lbs (57.0kg)
55 Gallon48 x 13 x 2146.5lbs (21.1kg)93.0lbs (42.2kg)139lbs (63.3kg)
65 Gallon36 x 18 x 2441.8lbs (19.0kg)83.7lbs (38.0kg)125lbs (57.0kg)
75 Gallon48 x 18 x 2155.8lbs (25.3kg)111lbs (50.6kg)167lbs (75.9kg)
90 Gallon48 x 18 x 2455.8lbs (25.3kg)111lbs (50.6kg)167lbs (75.9kg)
125 Gallon72 x 18 x 2183.7lbs (38.0kg)167lbs (76.0kg)251lbs (114.0kg)
150 Gallon72 x 18 x 2883.7lbs (38.0kg)167lbs (76.0kg)251lbs (114.0kg)
180 Gallon72 x 24 x 25111.5lbs (50.6kg)223lbs (101kg)334lbs (151kg)

How Much Play Sand/Pool Filter Sand Does My Aquarium Need?

Play sand and pool filter sand are both very popular in aquariums today. Sand looks amazing and is a great substrate if you are looking to keep any fish that sift through the substrate looking for food.

For a 1” (2.5cm) layer of either play sand or pool filter sand, you will need about 8lbs (3.6kg) per square foot of aquarium footprint. This means, for a 12” x 24” (30cm x 60cm) aquarium you will need roughly 21lbs (9.5kg) of either play sand or pool filter sand.

You can use the table below to work out how much play sand or pool filter sand you will need for your aquarium.

Aquarium VolumeAquarium Size (L x W x H inches)1″ Layer2″ Layer3″ Layer
20 Gallon High24 x 12 x 1616lbs (7.25kg)32lbs (14.5)48lbs (21.75kg)
20 Gallon Long30 x 12 x 1220lbs (9.1kg)40lbs (18.2kg)60lbs (27.3kg)
25 Gallon24 x 12 x 2016lbs (7.25kg)32lbs (14.5)48lbs (21.75kg)
29 Gallon30 x 12 x 1820lbs (9.1kg)40lbs (18.2kg)60lbs (27.3kg)
30 Gallon Breeder36 x 18 x 1236lbs (16.3kg)72lbs (32.6kg)108lbs (48.9kg)
40 Gallon Long48 x 12 x 1632lbs (14.5kg)64lbs (29.0kg)96lbs (43.5kg)
40 Gallon Breeder36 x 18 x 1636lbs (16.3kg)72lbs (32.6kg)108lbs (48.9kg)
50 Gallon36 x 18 x 1936lbs (16.3kg)72lbs (32.6kg)108lbs (48.9kg)
55 Gallon48 x 13 x 2140lbs (18.1kg)80lbs (36.2kg)120lbs (54.3kg)
65 Gallon36 x 18 x 2436lbs (16.3kg)72lbs (32.6kg)108lbs (48.9kg)
75 Gallon48 x 18 x 2148lbs (21.7kg)96lbs (43.4kg)144lbs (65.3kg)
90 Gallon48 x 18 x 2448lbs (21.7kg)96lbs (43.4kg)144lbs (65.3kg)
125 Gallon72 x 18 x 2172lbs (32.5kg)144lbs (65.0kg)216lbs (97.5kg)
150 Gallon72 x 18 x 2872lbs (32.5kg)144lbs (65.0kg)216lbs (97.5kg)
180 Gallon72 x 24 x 2596lbs (43.5kg)192lbs (87.0kg)288lbs (130.0kg)
FairmountSantrol AquaQuartz-50 Pool Filter 20-Grade Silica Sand 50 Pounds, White
12,302 Reviews
FairmountSantrol AquaQuartz-50 Pool Filter 20-Grade Silica Sand 50 Pounds, White
  • Ecologically safe sand does not solidify and will help prevent clogging and channeling
  • 100% natural sand is chemical free and backwashes easily and evenly
  • Filters out insects, leaves, oils, dirt, dust, hair and algae from pool water
  • Odorless, Premium #20 Grade swimming pool sand filter Media
  • Does not stain and ensures easy maintenance at a lower cost

Last update on 2022-11-23 / Affiliate links / Images from Amazon Product Advertising API

How Much Fluval Stratum Do I Need?

Fluval Stratum is mineral-rich and ideal for planted aquariums and shrimp aquariums. Fluval Stratum is available in bags weighing 4.4lbs (2kg), 8.8lbs (4kg), and 17.6lbs (8kg).

For a 1” (2.5cm) deep layer of Fluval Stratum, you will need roughly 5.5lbs (2.4kg) per square foot of aquarium footprint. This means, for a 12” x 24” (30cm x 60cm) aquarium, you will need about 11lbs (4.8kg) of Fluval Stratum.

You can use the table below to work out how much Fluval Stratum you will need for your aquarium.

Aquarium VolumeAquarium Size (L x W x H inches)1″ Layer2″ Layer3″ Layer
20 Gallon High24 x 12 x 1611lbs (5.0kg)22lbs (10.0kg)33lbs (15.0kg)
20 Gallon Long30 x 12 x 1213.5lbs (6.1kg)27.0lbs (12.2kg)40.5lbs (18.3kg)
25 Gallon24 x 12 x 2011lbs (5.0kg)22lbs (10.0kg)33lbs (15.0kg)
29 Gallon30 x 12 x 1813.5lbs (6.1kg)27.0lbs (12.2kg)40.5lbs (18.3kg)
30 Gallon Breeder36 x 18 x 1224.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
40 Gallon Long48 x 12 x 1622lbs (10.0kg)44lbs (20.0kg)66lbs (40.0kg)
40 Gallon Breeder36 x 18 x 1624.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
50 Gallon36 x 18 x 1924.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
55 Gallon48 x 13 x 2127.5lbs (12.5kg)55.0lbs (25.0kg)73.5lbs (37.5kg)
65 Gallon36 x 18 x 2424.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
75 Gallon48 x 18 x 2133lbs (15.0kg)66lbs (30.0kg)99lbs (45.0kg)
90 Gallon48 x 18 x 2433lbs (15.0kg)66lbs (30.0kg)99lbs (45.0kg)
125 Gallon72 x 18 x 2149.5lbs (22.5kg)99lbs (45.0kg)148.5lbs (67.5kg)
150 Gallon72 x 18 x 2849.5lbs (22.5kg)99lbs (45.0kg)148.5lbs (67.5kg)
180 Gallon72 x 24 x 2566lbs (30.0kg)132lbs (60.0kg)198lbs (90.0kg)
Sale
Fluval Plant and Shrimp Stratum, For Fish Tanks, 8.8 lbs.,
9,686 Reviews
Fluval Plant and Shrimp Stratum, For Fish Tanks, 8.8 lbs.,
  • Fluval Stratum is made of mineral rich volcanic soil
  • Stimulates strong aquarium plant growth
  • Promotes neutral to mildly acidic pH
  • Suitable for live plants or shrimp
  • 8.8 lb. bag

Last update on 2022-11-23 / Affiliate links / Images from Amazon Product Advertising API

How Much Eco-Complete Do I Need?

Eco-Complete is made from basaltic volcanic soil and is designed to be used in planted aquariums. Eco-Complete is sold in 20lbs (9.07kg) and 40lbs (18.14kg) bags.

For a 1” (2.5cm) deep layer of Eco-Complete, you will need roughly 8lbs (3.6kg) of Eco-Complete per square foot of aquarium footprint. This means, for a 12” x 24” (30cm x 60cm) aquarium you will require about 16lbs (7.2kg) of Eco-Complete

You can use the table below to work out how much Eco-Complete you will need for your aquarium.



Aquarium VolumeAquarium Size (L x W x H inches)1″ Layer2″ Layer3″ Layer
20 Gallon High24 x 12 x 1616lbs (7.25kg)32lbs (14.5)48lbs (21.75kg)
20 Gallon Long30 x 12 x 1220lbs (9.1kg)40lbs (18.2kg)60lbs (27.3kg)
25 Gallon24 x 12 x 2016lbs (7.25kg)32lbs (14.5)48lbs (21.75kg)
29 Gallon30 x 12 x 1820lbs (9.1kg)40lbs (18.2kg)60lbs (27.3kg)
30 Gallon Breeder36 x 18 x 1236lbs (16.3kg)72lbs (32.6kg)108lbs (48.9kg)
40 Gallon Long48 x 12 x 1632lbs (14.5kg)64lbs (29.0kg)96lbs (43.5kg)
40 Gallon Breeder36 x 18 x 1636lbs (16.3kg)72lbs (32.6kg)108lbs (48.9kg)
50 Gallon36 x 18 x 1936lbs (16.3kg)72lbs (32.6kg)108lbs (48.9kg)
55 Gallon48 x 13 x 2140lbs (18.1kg)80lbs (36.2kg)120lbs (54.3kg)
65 Gallon36 x 18 x 2436lbs (16.3kg)72lbs (32.6kg)108lbs (48.9kg)
75 Gallon48 x 18 x 2148lbs (21.7kg)96lbs (43.4kg)144lbs (65.3kg)
90 Gallon48 x 18 x 2448lbs (21.7kg)96lbs (43.4kg)144lbs (65.3kg)
125 Gallon72 x 18 x 2172lbs (32.5kg)144lbs (65.3kg)216lbs (97.5kg)
150 Gallon72 x 18 x 2872lbs (32.5kg)144lbs (65.3kg)216lbs (97.5kg)
180 Gallon72 x 24 x 2596lbs (43.4kg)192lbs (87.0kg)288lbs (130.0kg)

How Much Seachem Flourite Or Flourite Black Do I Need?

Seachem Flourite and Flourite Black are described as ‘porous clay gravel for the natural planted aquarium’. Both Flourite and Flourite Black come in 7.7lbs (3.5kg) and 15.4 (7kg) bags.

For a 1” (2.5cm) deep layer of Seachem Flourite or Flourite Black, you will want about 5.5lbs (2.5kg) per square foot of aquarium footprint. This means, for a 12” x 24” (30cm x 60cm) aquarium, you would need about 11lbs (5kg) of either Flourite or Flourite Black.

You can use the table below to work out how much Flourite or Flourite Black you will need for your aquarium.

Aquarium VolumeAquarium Size (L x W x H inches)1″ Layer2″ Layer3″ Layer
20 Gallon High24 x 12 x 1611lbs (5.0kg)22lbs (10.0kg)33lbs (15.0kg)
20 Gallon Long30 x 12 x 1213.5lbs (6.1kg)27.0lbs (12.2kg)40.5lbs (18.3kg)
25 Gallon24 x 12 x 2011lbs (5.0kg)22lbs (10.0kg)33lbs (15.0kg)
29 Gallon30 x 12 x 1813.5lbs (6.1kg)27.0lbs (12.2kg)40.5lbs (18.3kg)
30 Gallon Breeder36 x 18 x 1224.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
40 Gallon Long48 x 12 x 1622lbs (10.0kg)44lbs (20.0kg)66lbs (40.0kg)
40 Gallon Breeder36 x 18 x 1624.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
50 Gallon36 x 18 x 1924.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
55 Gallon48 x 13 x 2127.5lbs (12.5kg)55.0lbs (25.0kg)73.5lbs (37.5kg)
65 Gallon36 x 18 x 2424.5lbs (11.1kg)49.0lbs (22.2kg)73.5lbs (33.3kg)
75 Gallon48 x 18 x 2133lbs (15.0kg)66lbs (30.0kg)99lbs (45.0kg)
90 Gallon48 x 18 x 2433lbs (15.0kg)66lbs (30.0kg)99lbs (45.0kg)
125 Gallon72 x 18 x 2149.5lbs (22.5kg)99lbs (45.0kg)148.5lbs (67.5kg)
150 Gallon72 x 18 x 2849.5lbs (22.5kg)99lbs (45.0kg)148.5lbs (67.5kg)
180 Gallon72 x 24 x 2566lbs (30.0kg)132lbs (60.0kg)198lbs (90.0kg)
Sale
Fluval Plant and Shrimp Stratum, For Fish Tanks, 8.8 lbs.,
9,686 Reviews
Fluval Plant and Shrimp Stratum, For Fish Tanks, 8.8 lbs.,
  • Fluval Stratum is made of mineral rich volcanic soil
  • Stimulates strong aquarium plant growth
  • Promotes neutral to mildly acidic pH
  • Suitable for live plants or shrimp
  • 8.8 lb. bag

Last update on 2022-11-23 / Affiliate links / Images from Amazon Product Advertising API

What Is Substrate?

Aquarium substrate is essentially anything that is placed on the bottom of the aquarium. The substrate can be something that is designed to look natural, such as gravel or sand, or it can be something that is bright and colorful such as brightly colored gravel.

Some substrates are totally inert and have no effect on the aquarium water. Aquarium gravel is a great example of this. Aquarium-safe gravel will have no effect on aquarium pH or water hardness and doesn’t add or remove nutrients from the water column.

Other substrates, such as Amazonia Soil by ADA have been actively designed to affect the water chemistry one way or another. Crushed Coral is another substrate that can affect water chemistry. If you have acidic water and you use crushed coral as a substrate, the acidic water will break down the crushed coral over time, raising the hardness of the aquarium water.

Does An Aquarium Need Substrate?

No, aquariums do not have to have substrate. Many commercial breeders and hobbyists with multiple tanks keep their fish in bare bottom aquariums. There are pros and cons to both having and not having a substrate.

Bare bottom aquariums can be easily kept clean as any uneaten food and fish poop can be simply siphoned out whenever it settles on the bottom. On the flip side, bare bottom aquariums can look very sterile, and, if you don’t siphon the waste out on a regular basis, they can look very messy.




About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James
Editor