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How Much Crushed Coral To Raise The pH In Your Aquarium?

Crushed coral is one of the main ways that people within the fish keeping hobby are able to quickly, easily, and cheaply tweak the pH levels of their aquariums as required.

The main problem that we see people reaching out and asking questions about is how much crushed coral is needed to raise pH in their tanks as well as how they should actually use the crushed coral in their tanks to tweak pH.

A commercially available crushed coral product is usually used in a ratio of 1 pound of crushed coral per 10 gallons of aquarium water and you simply mix it with your substrate to let the coral dissolve over time to tweak the pH levels of your tank.

Some people do try to make their own crushed coral products but they tend not to be as reliable as the commercial products that tend to offer a more predictable change in water pH levels.

There are a range of different crushed coral products on the market so be sure to use one that has been specifically designed to be used to tweak the pH levels of your aquarium rather than as a generic substrate.

The generic substrate crushed coral products can have different ratios of crushed coral in them making it harder to work out the calculations for how much crushed coral you will have to add to your tank to get the same adjustment in the pH levels.

How Do You Use Crushed Coral To Raise pH Levels?

Commercially available crushed coral products are very easy to use and you usually just add the crushed coral to your tank, often mixed with your substrate in the recommended ratio on the label of your crushed coral and then leave it to change the pH of your tank.

The lower your current pH level is for your tank water, the faster the crushed coral will dissolve in an average tank.

This is why crushed coral is such a popular option for tweaking the pH levels within aquariums as it is a natural way to rapidly tweak pH levels if required.

In addition to this, crushed coral is usually very budget friendly and very beginner friendly too making it one of the better options on the market.

There are a number of alternatives that you are able to use to adjust your pH levels as required but more and more people within the fish keeping community are moving away from artificial chemical treatments in favor of natural treatments.

There are a number of aquarium filters and crushed coral baskets on the market that can work with crushed coral allowing you to use the product in a different way but the majority of people really have no need for them.

Simply following the normal instructions on the label of your crushed coral and adding it to your tank in the amount required will be enough to get the job done and rapidly start changing your tanks pH levels.

How Much Crushed Coral To Raise pH Levels?

The majority of crushed coral products that are designed to be used to tweak pH levels will have easy to follow instructions on their packaging that may change from product to product.

The majority of them are usually used in a ratio of one point of crushed coral per ten gallons of aquarium water but some products will have slightly different ratios so always check the label for correct usage ratios.

If you do have to adjust your pH levels by a large amount then some people will add larger amounts of crushed coral to their aquarium at the very start but this is usually not recommended as it does make it more difficult to predict the final pH levels.

Although it is true that the changes to your tank pH level will slow and the crushed coral will eventually stop dissolving as the pH levels normalise, some people do not need the pH levels of their tank to be as high as that.

This is why we would still always recommend that you stick to the standard usage ratio of the crushed coral you have as recommended on the label of the product.

Leave the crushed coral to do its thing and change the pH level of your tank and then reassess the needs of your tank if the pH level still needs to be adjusted after the first treatment.

As you now have some data to workout how much one pound of the crushed coral that you have per ten gallons of water adjusted the pH level of your tank, you are able to plan out fractional dosages of the crushed coral.

Just keep in mind that the closer and closer you get the pH level of your tanks water to normalization where your coral will not dissolve, the slower the changes will be as it takes more time for the crushed coral to dissolve.

How Long Does It Take Crushed Coral To Raise pH?

The majority of people will see the pH level in their aquarium rise and stabilize within the course of around a week no matter the situation.

This is due to the coral disolving quicker with a lower pH and slower with a slightly higher pH usually resulting in the same five to ten day adjustment period for the coral to raise your tanks pH levels.

As we mentioned earlier in the article though, there are a number of different crushed coral products on the markets these days and not all of them are pure curshed coral that have been designed to be used to adjust the pH levels of your aquarium.

This means that some of the crushed corals that come mixed with sand, gravel or other types of substrate may take a different amount of time to raise the pH levels of your aquarium’s water to the target pH level.

The ratio of crushed coral to the amount of water into your tank also plays a huge role in how quickly your pH levels will rise.

If you do intentionally need your pH levels to rise gradually over an extended period of time then you can resuce the crushed coral ratio but we would never recommend that you attempt to speed up the process as explained earlier.

Does Crushed Coral Raise Gh And Kh?

Crushed coral can tweak the Gh and Kh of your aquarium water when used but the changes to the hardness of your water when using crushed coral are often not as predictable as the changes to pH level when using crushed coral.

Thankfully, the Gh and Kh levels tend not to change drastically when using crushed coral so the majority of people shouldn’t have major problems with their intended levels being knocked out of target parameters.

Still, if you are using some crushed coral in your aquarium then we would highly recommend that you do your best to monitor your Gh and Kh levels as closely as possible, especially if this is your first time using crushed coral in your tank.

If you have sensitive fish, corals or anemones in your tank then this can become even more important as even slight changes to Gh and Kh levels can cause problems.

Thankfully, the majority of people who read out articles tend to be either beginners to fish keeping or trying something new in a pretty generic tank with hardy fish and plants.

This reduces the chances of having any problems with your Gh and Kh levels but we would recommend that you do still monitor them.

At What pH Does Crushed Coral Stop Dissolving?

The majority of crushed coral products will stop dissolving at a pH of 8.2 but there are a small number of products that will stop dissolving slightly lower than this due to the corals used in the product.

The majority of people will be using a regular crushed coral product though and planning out their stabilization point at a pH of 8.2 will be fine.

As we covered earlier in the article, not everyone will need to raise their pH levels to 8.2 so this is why we never recommend that you try to increase the pH chance pace by adding too much coral to your aquarium as you may accidentally raise your pH levels too much.

Slow and steady usually wins the race, especially in an aquarium with sensitive fish or corals in there where they need steady or slowly changing water parameters.

When you build up more experience with using crushed coral to tweak the pH levels of your aquarium, you will often be able to tweak the amount of crushed coral that you add to your tank as required to get the results you require.

This can take some testing though but adjusting the crushed coral ratio that you add to your tank can be a reliable way to slightly change pH levels once you get used to how your aquarium will react.

Can I Use Crushed Coral In A Freshwater Aquarium?

You can use crushed coral in a freshwater aquarium as a reliable way to to tweak your pH levels without having to use chemical products.

Although the majority of people who use crushed coral to manage pH do it in a marine tank, the number of people who use it for a freshwater aquarium is increasing as crushed coral becomes more popular.

There is a common misconception that you shouldn’t use crushed coral in freshwater aquariums due to the salinity levels not letting the coral dissolve correctly but this is not correct. Crushed coral dissolved to due reaction with the acids and alkalines in the water of your aquarium rather than the salinity.

Even though there is plenty of evidence of this, we still commonly see people on social media talking about avoiding using crushed coral in a freshwater aquarium but plenty of people do it without issue.

Just remember that all of the fish, plants, snails, shrimp, and other living creatures in your aquarium will have to be able to tolerate the new pH level that the crushed coral will set in your aquarium.

You will usually find that the majority of the commonly kept things in freshwater tanks are easily able to take the pH change without issue though.


That brings our article going over how much crushed coral you need to raise ph levels in your aquarium to an end. We hope that we have been able to help you better understand that crushed coral is an excellent option for anyone wanting a cheap and easy way to adjust the pH levels in their tank. It is a natural method too that is also making crushed coral rapidly grow in popularity as more people look to avoid cheimcal based options.