One of the first things to figure out when setting up your saltwater tank is learning about the sand you put in it. You are likely going to use live sand, and there are a lot of different choices. Non-living sand is an option, but it costs about the same, and it is not as available in a lot of online vendors
So, how much sand for a saltwater aquarium? It is recommended to use about 1 1/2 to 2 inches or around 1.4 pounds of sand per gallon. This would be around 75 pounds for a 55 gallon saltwater tank.
Common Amounts of Sand Based On Tank Size
(Note: This is for the average tank shape per volume. The amount of sand will depend on the length and width of you aquarium. Adding a greater height will increase the volume but does not necessarily increase the amount of sand bed needed.)
For reference in the below chart, the 55 gallon dimensions are 48x13x20. The 90 gallon would be 48x18x24.
| Tank Size | 1 Inch Depth | 2 Inch Depth |
| 20 Gallon Tank | 10 lbs. | 20 lbs. |
| 30 Gallon Tank | 25 lbs. | 50 lbs. |
| 40 Gallon Tank | 35 lbs. | 65 lbs. |
| 55 Gallon Tank | 40 lbs. | 75 lbs. |
| 75 Gallon Tank | 45 lbs. | 90 lbs. |
| 90 Gallon Tank | 45 lbs. | 90 lbs. |
| 120 Gallon Tank | 60 lbs. | 120 lbs. |
| 180 Gallon Tank | 90 lbs. | 180 lbs. |
| 220 Gallon Tank | 90 lbs. | 180 lbs. |
What Is Live Sand?
Live sand is basically a substrate that has been cultured with beneficial bacteria. This is very tiny bacteria that serves as a biological filter for your saltwater tank.
In the first couple of inches of a sand, aerobic bacteria will break down waste and create nitrates. This will occur in all saltwater tanks, it’s just a matter of seeding your tank with it initially, or letting it seed naturally over time.
Basically, sand is pumped up from below the ocean floor, and then it is dried. Later, it is sifted into different sizes, and then packaged into bags. A little bit of water is added to each bag along with dormant bacteria.
This dormant bacteria becomes active ones it is added to the correct environment, like your saltwater tank.
How To Choose The Best Sand For Your Aquarium
When choosing the type of sand for your saltwater tank, it is a good idea to understand what kind of tank you plan on having, and what type of look are you going for. There are several factors to consider.
- Color
- Size
- Depth
- Tank Inhabitants
Most sand is your standard beige color, but you can get some with specks of pink in it like Fiji Pink. You can also get black sand which is formed from volcanic ash in Hawaii. If you decided to go with a non-standard color, it may limit your options on sand sizes.
Another important factor to consider is the size of the substrate. This is for practical and aesthetic reasons. What do you want it to look like, and will it affect your tank.
Fine sand is more likely to get blown around by your power heads, and this may leave bare spots and cloud up your water. Course sand is more likely to trap detritus and it does not have that “beachy” look.
If you want to go with a deep sand bed, meaning more than 3 inches, it is better to use more fine sand. Either way, just make sure that you have some critters that can stir up you sand like conch snails.
The type and size of sand can also determine what you can and cannot add to your tank. If you plan to have sand sifters like a Gobi, you need to have a good depth and a grain size . You will need at least 2 inches depth for Gobis and Wrasses.
If none of your inhabitants have certain requirements, then you are free to choose more options. However, keep in mind that if you decide down the road that you must have a Wrasse and Gobi, it will be very difficult to work with this.
Do I Have To Put Sand In My Tank?
No, you do not have to put live sand in your tank. Many people run very successful aquariums with a bare bottom, so it is not necessary. Yes, you lose the look of a natural sea floor, and you lose the benefit of biological filtration.
The loss in the filtration is not that big of a deal because you will get that from other sources in your setup. It really comes down to look.
Sand Bed Calculator
Marine Depot offers a handy calculator that looks at the dimensions of your aquarium and the type of sand you are getting. It doesn’t get any easier that that!
https://www.marinedepot.com/md_educationcenter_calculators_sand_bed_calculator.html
Summary of How Much Sand For Your Saltwater Tank
There are many important things to consider when determining how much sand you need in your tank. This is crucial to figure out before you set up your aquarium because not only does it have aesthetic consequences, it also has practical ones too.
Feel free to leave a comment below if we left anything off.
