How Many Pounds Of Live Rock Per Gallon? A Complete Guide For Easier Understanding

Last Updated on June 4, 2022 by Guillermina

Wondering how many pounds of live rock per gallon of aquarium water? Stay with us and find out the exact calculation.

The role of live rock in your aquarium is of vital importance. However, there is one misconception, namely, some people believe that live rock itself is alive. What makes it “live” are the many forms of micro-and macroscopic that live inside and outside of it.

How many pounds of live rock per gallon? – This is one of the most common questions, especially among novice aquarists. You know what? We think you might be surprised to find out the correct answer. Well, keep reading…

What Exactly Is Live Rock?

In short, live rock is made from the aragonite skeletons of dead corals and other organisms; it is in most cases covered in coralline algae and in other microscopic organisms as well. The cover layer functions as a biological filter and serves to diversify the saltwater aquarium environment.

Accordingly, it is important to emphasize that once introduced into the aquarium the live rock becomes the main biological nitrification base while improving the appearance of the aquarium and providing shelter for the inhabitants.

It brings many life forms into your aquarium, such as numerous algae, bacteria, and small invertebrates, altogether contributing to a better quality of life for your underwater community.

Lastly, keep in mind that no matter what type of live rock you choose to use, a biological filter base has to cycle and settle to make everything run properly. This ultimately applies to curing live rock as well. We are now slowly approaching the focus of this article, the answer to the question “how many pounds of live rock per gallon”, so let’s get to the point.

 Can you put too much live rock in a tank?

How Many Pounds of Live Rock per Gallon of Water?

The old, general rule for calculating how many pounds of live rock per gallon of aquarium water is – 1-2 pounds (0.45-0.9kg) of live rock for every gallon (3.8L) of aquarium volume.

To make it easier to understand, here are some simple examples:

  • For an aquarium with a volume of 55 gallons (208L), you should add 55-110 pounds (25-50kg) of live rock.
  • For an aquarium with a volume of 90-gallon (341L), you are supposed to add 90-180 pounds (41-82kg) of this material.

However, as usual with any “rule of thumb”, there are some variables that come into play. Accordingly, it is necessary to pay attention to the density of the rock. Based on this, we can conclude that dense, heavy rock, (e.g. 100 pounds or 45kg) takes up less space than the same weight in lightweight, porous rock.

Furthermore, to some aquarists, this rule seems like a bad idea, and here’s why. If you want to succeed, everything you decide to have in your saltwater aquarium needs to be planned ahead of time, both livestock and live rocks.

Don’t forget that the dimensions of your tank play a big part in all of this, and accordingly if you have a 3-foot long tank, you may not fit as many live rocks as you would with a standard 4-foot aquarium tank.

Another very important factor is your budget because the live rocks are very valuable. For some people having 1 or 2 pounds per gallon is simply not possible or desirable, and accordingly, they will try in every way to get away with much less and still have a very healthy tank.

After all, an aquarist can be completely satisfied with a 32-gallon aquarium tank with only 20 pounds of live rock in the setup, or a 120-gallon tank with only 70 pounds. It’s all a matter of your personal taste.

Related article How Much Gravel For A 75-Gallon Aquarium?

Now that you’ve read this, you can get an idea of how many pounds of live rock per gallon of aquarium water.

Benefits of Using Live Rocks In Your Aquarium

In addition to performing biological filtration, live rock has a number of benefits.

  • Since it was once part of a living coral reef and it leaches into your water, live rocks help stabilize the Ph of your water.
  • Once added to your tank, it will provide a solid foundation for the rest of your reef to build on.
  • Live rock is very porous and accordingly has the ability to provide a massive surface area for beneficial Nitrosomonas and Nitrobacter Bacteria to colonize. This feature helps to get rid of harmful nitrates and ammonia from your aquarium water.
  • A wide range of different types of rock, sizes, and shapes available give you endless flexibility to create the ideal aquascape.

To End – How Many Pounds Of Live Rock Per Gallon?

 How expensive is live rock?

Live rock is the foundation for any thriving aquarium tank. In addition, it is the base of almost every aquarium decor.

For all those who are wondering how many pounds of live rock per gallon, we can only say – the amount depends on what you want your aquarium to look like and how much you want to spend. However, you can always follow the standard rule that suggests using 1-2 pounds (0.45-0.9kg) of live rock for every gallon (3.8L) of aquarium volume.

Do you use live rocks in your aquarium tank? Write us your answers in the section below. We are expecting you.

You might like Aquarium Check Valve Direction; A Quick & Easy Guide For Easier Handling


How Much Does Live Rock Usually Cost?

Depending on the manufacturer, it can cost anywhere from $ 5 to $ 12 a pound. What we like most is that there are always people breaking down tanks and selling their used live rocks from $ 2 to $ 4 a pound. Accordingly, everyone can find something within their own budget.

Can You Put Too Much Live Rock In A Tank?

Since this is where bacteria colonize, and toxic compositions brakes down, you can never have too many live rocks in your aquarium tank. In any case, it would be better not to overcrowd because even top-quality live rocks can be quickly turned into a dead base rocks if mass quantities are introduced all at once.

Does Live Rock Need Light?

Live rock doesn't seem to need light, however, if you want different photosynthetic organisms to thrive on it, then yes, you will need it.

How Expensive Is Live Rock?

Live rocks are not expensive at all. Their price generally varies somewhere between $ 5 and $ 12 a pound. In addition, you can get already used rocks; this option is much more affordable than buying new ones.