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Saltwater Tank Equipment

How Much Live Rock For A Saltwater Aquarium

By January 30, 2020No Comments
aquarium live rock

How Much Live Rock For A Saltwater Aquarium

A good rule to figure out how much rock or live rock is needed for your saltwater tank is 1.5 pounds of rock per gallon of water. Or, that would be 1kg per 10 Liters of water. This is just an average and there definitely is some wiggle room in that amount.

Lets break that down for some common aquarium sizes.

  • 30 Gallon Aquarium: 45 pounds of rock
  • 40 Gallon Aquarium: 60 pounds of rock
  • 60 Gallon Aquarium: 90 pounds of rock
  • 75 Gallon Aquarium: 112 pounds of rock
  • 90 Gallon Aquarium: 125 pounds of rock
  • 100 Gallon Aquarium: 150 pounds of rock
  • 120 Gallon Aquarium: 180 pounds of rock
  • 220 Gallon Aquarium: 340 pounds of rock

Do I really have to use that amount? As stated before, that is a standard starting point, and you can certainly go up or down depending on your needs and budget. If you are starting a new 30 gallon tank, you probably don’t need 45 pounds of rock if you plan to have a few small corals and a couple of clown fish.

If you are tight on budget, 1 pound of rock will work fine in most situations. You can always add more to your sump tank later if needed, that way you wont affect how your display tank looks.

Why Do I Need Live Rock

You need live rock in your tank to house beneficial bacteria to filter and to keep your tank cycled properly. It also provides shelter and aesthetics.

What Type Of Rock Do I Need

how much live rock

There are several options available when it comes to rock for saltwater tanks. You can purchase dry rock, or live rock. It is generally sold by the pound, and it is pretty common for a standard size dry rock to weigh around 5 pounds. Granted, this can vary, but most LFS (Local Fish Stores) I have been to sell rocks in the range of 4-6 pounds.

Live rock is something that you will see in tanks that is already loaded with beneficial bacteria, and it is basically rock that comes straight from the ocean. It can also have undesirable pests and parasites on it.

Dry rock is shipped to you dry and is basically life less. It will become populated with beneficial bacteria over time when it is in your aquarium.

Personally, I prefer Dry rock, because I do not want the risk of adding pests to a new tank that can inhabit live rock. It is also a little bit cheaper, especially if you have to order it online. Most of the live rock I have seen in big box pet stores does not look that great.

It can come in various types, sizes, and shapes, so you should be able to sculpt an underwater garden for your display tank. Just pick what you think looks best, and what fits your budget.

There are different types like Fiji and Reef Saver, just grab what suits you.


Figuring out how much live rock for a saltwater tank is easy. That is just simple math. Choosing what type of rock and how to set it up takes a little more time. As we discussed, make a choice of live or dry rock. You can also do a little of both. A little bit of live rock can be used to seed your tank so that your dry rock will get loaded with bacteria quicker.

Again, I am not a fan of purchasing live rock, as you can use products to add live bacteria to your tank to seed your dry rock.


My name is James, and I am the founder of Saltwatercoraltank. I love everything about the ocean, and my main hobby is saltwater aquariums. Currently, I have 3 tanks that I maintain. I have a 130 gallon mixed as my main, and I prefer softies.

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