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How To Use Limestone For An Aquarium!

With there being do many people who are new to aquarium keeping in the hobby right now, we have seen a number of people having issues maintaining consistent water parameters over and over again.

It is common for people to recommend the use of limestone for aquariums as a way to tweak your water parameters to the levels that you require but it can be a little controversial within the community, especially when discussed on social media.

This is usually due to there being a number of variables involved in adding limestone to your aquarium and it not always being a suitable option depending on your current water parameters and what you actually want to do with your water parameters moving forward.

On top of that, there is also the discussion of using limestone rocks or ground limestone as both act in a slightly different way.

In our opinion, normal limestone rocks are the better option, especially if you are a beginner as they are easier to use.

Throughout the rest of the article, we will be presuming that you have taken this part as ground limestone usually takes more time and effort to prep for use in the aquarium and can be harder to get the same results as normal limestone rocks.

Is Limestone OK For Fish Tanks?

Limestone is generally considered safe for fish tanks containing both live plants and live fish that need a higher pH, KH, and GH level with many people using limestone as a cheap way to achieve this.

If your aquarium already has a high pH, KH or GH then we would not recommend that you add additional limestone unless it is in some very specific situations that are rare.

You are able to use limestone in your aquarium to your advantage and as a quick and easy way to tweak your water parameters by increasing some core vitals.

The limestone can usually be integrated into most aquascapes easily too due to the rocks being available in a wide range of sizes and shapes.

This can allow you to integrate the limestone into your aquarium to increase your pH, KH, and GH levels if needed without it looking out of place.

Some people will just choose to add a limestone rock into their aquarium without actually trying to integrate it into the overall look of the tank though, it all depends on you and how you want to run your tank.

How Does Limestone Change Your Aquariums Water Parameters?

Limestone has a number of effects on the water parameters of your aquarium once added. Depending on your current water parameters and what you want to do with your parameters, these can either be an advantage or a disadvantage.

There are plenty of aquarium safe rocks that you are able to use in your aquarium that will not tweak your water parameters though so if you just want something for decoration, limestone is probably not the best option.

Does Limestone Raise KH And GH In An Aquarium?

Limestone contains a large amount of calcium carbonate that will slowly dissolve into the water of your aquarium.

Over time, the calcium will increase the GH level of your tank while the carbonate will increase the KH level of the tank, sometimes by substantial levels depending on how much limestone you add to your tank.

Does Limestone Raise pH In An Aquarium?

Limestone will raise the pH levels of your aquarium and can do so surprisingly quickly. The more limestone that you add to your aquarium, the quicker it will increase the pH levels and the higher they will be able to get.

Using ground limestone over actual limestone rocks will raise the pH of your aquarium even quicker too.

Are Live Plants Ok With Limestone In Their Aquarium?

Limestone can be used in an aquarium with many types of live plants provided the plants are fine with a higher pH level.

Some of the more sensitive plants can struggle with a higher pH level so always check the required water parameters for the live plants that you intend to keep in your tank.

The increase in the KH and GH levels can also present an issue for some of the more sensitive live aquatic plants but this tends to be less common than the changes to pH.

If your water parameters in your aquarium are already low on pH, KH, and GH then limestone can be used to your advantage to increase them to a level that is within the parameters of the plants that you are wanting to keep too.

Some people will worry about the pH and KH swings in their tanks when they first add the limestone to their aquarium.

This does tend to be more of an issue for sensitive fish species than plants and the majority of plants will be fine due to the swing usually only lasting around a day.

Are Fish Ok With Limestone In Their Aquarium?

If you have soft water with a low pH in your aquarium then limestone can be a very beginner-friendly way to increase the levels to within the parameters of your fish safely.

Some people will choose to use ground up calcium carbonate instead of limestone but the process does tend to be more difficult than just adding limestone to your tank.

The swing levels and time frame of using crush up, pure calcium carbonate also tend to have more of an effect on fish, shrimp, snails, amphibians, and any other live animal in the tank too.

Limestone tends to have a more gradual swing making it the safer option for fish but you always have to factor in the recommended water parameters of your fish when adding limestone to your aquarium.

Keep in mind that some fish are very sensitive to their water parameters and limestone will not be a suitable way to increase your pH, KH, and GH for them but many fish will be totally fine.

Our recommendation would be to check the specific fish species that you keep and check if they are ok with limestone.


That brings our article going over how you are able to use limestone for an aquarium to an end. We hope that we have been able to help you better understand when you should be using limestone in your aquarium as it is a beginner-friendly way to increase the Ph, KH, and GH of your tank without having to break the bank. You are usually able to use limestone for cheap too without having to buy any expensive equipment helping to keep your costs as low as possible too.