For a very long time, granite has remained one of the most popular choices among the rocks you can use in your fish tanks. Its ease of accessibility, inertness and aesthetics have meant that many people don’t pay attention to other options.
In this blog, we will talk about how to use granite, explain how to select safe stones for your fish tanks and go through the top aquarium materials you should be using in your fish tank.
Is granite safe for fish tanks
Granite, like other igneous rocks, have very little effect on the water. As granite is an inert stone, simple to cut into equal tidy pieces, and does not deteriorate over time, it tends to remain constant over time and is relatively harmless to use in fish tanks.
If granite is introduced to a soft water setting and you notice that the PH begins to climb, rusting iron minerals may be present amongst the rock. It is important that you remove the granite as soon as possible and properly clean the stone before reintroducing it back into your tank to avoid any negative effects.
List of rocks that should be avoided and that are safe to use
Some of the rocks that you should avoid using in your fish tank are the ones that are particularly calcareous, which means they contain a high percentage of calcium. Additionally, it is important to keep sharp-edged rocks away from your fish. Below you can find some of the rocks or cheap aquarium substrate that you can use in your fish tank.
| Rocks to Avoid | Rocks to Use |
| Shells or crushed coral | Slate |
| Geodes | Quartz |
| Marble | Granite |
| Dolomite | Lava Rock |
| Limestone | Sandstone |
Using granite in fish tanks
If you are wondering whether or not you should be using granite in your fish tank, it is important that you understand the advantages and disadvantages so that you can make an informed decision before you buy.
Advantages of using granite in fish tanks
Adding granite to your fish tanks can provide many benefits to the ecosystem within the tank and to the fish and plants that are currently thriving inside.
Very little impact on water properties
Granite has very little impact on the water in your tank due to it’s inert nature. When introduced, you can rest assured that the pH values and the hardness off the water will remain constant over time.
Difficult to fracture
It should be noted that the denseness of the granite stones are difficult to fracture. This makes it great for being sliced into smaller pieces without fracturing or smashing.
Retains heat
Granite is one of the most perfect fish tank stone types due to its ability to preserve and retain the heat of the fish tank after the lights have been turned off.
Disadvantages of using granite in fish tanks
Despite all the advantages that granite can bring to your fish tank, it is worth noting that there are some disadvantages that you should know about if you want to introduce granite in your fish tank.
May contain traces of iron
When buying granite stones, you should thoroughly wash them to ensure that any trace amount of iron is removed. Whilst these are favourable for plant life in a freshwater environment, it could actually be fatal to non-freshwater residents.
Granite is heavy
It is worth noting that granite is actually fairly heavy. If you choose to use this material, you need to make sure that your stand can hold the weight of all the granite before you introduce it to your fish tank or the tank could potentially fall and break.
How to clean granite rocks
When purchasing granite, it is important to clean it to remove trace irons that may be existing within the packet of stones. This is especially important so that they should not alter the pH of the water in the fish tank and also if you want to keep the color of the water constant and not make it a cloudy fish tank.
To do so, begin by filling a bucket halfway with cold water and putting the stone inside. Scrub each stone before re-dipping it in the cold water. Rinse the stone again, then immerse it in clean, cold water.
If the clear water no longer changes color, the granite is now clean and safe to use in the fish tank. To prevent the granite breaking down or losing its natural beauty, avoid using chemicals, strong force or boiling-hot water.
How to break granite to use in a fish tank
Granite has a toughness rating of six and is more difficult to crack than other varieties of aquarium rocks. A chisel and hammer set will be required to efficiently break it into smaller pieces.
If the pieces break into undesirable bits you can super glue the pieces back together and sand off into a smooth finish.
FAQs about putting granite in fish tanks
Yes, granite is safe for fish tanks as it is an inert stone that does not significantly impact the properties of the water. This makes it a suitable choice for fish tanks, providing a stable and safe environment for aquatic life. It is however, important to ensure that the granite is thoroughly cleaned and free from any potential contaminants before it is introduced into the fish tank.
Some rocks such as limestone are alkaline based and can neutralize the acidity level of the water, while other rock types such as granite, have next to no influence on pH levels.
Shells or crushed coral, geodes, marble, dolomite, and limestone are generally unsuitable for fish tanks mainly due to their mineral compositions. These rocks have the capacity to increase water hardness and pH levels, which can potentially harm fish by creating imbalances in the aquatic ecosystem.
Slate, quartz, granite, lava rock, black diamond blasting sand and sandstone are considered safe for fish tanks due to their inert nature and minimal impact on water chemistry. These rocks do not affect water parameters, and help to ensure stability in pH levels and hardness, which is crucial for fish health.
Although granite is inherently resistant to bacteria, this does not mean it is completely immune to pathogens. Sealing granite rock helps to prevent bacteria from growing in the microscopic fissures and pores keeping the water environment safe and clean.
The maximum amount of water that granite can absorb is between 0.8 and 0.01 percent.