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HomeAquarium & MaintenanceAquarium salt vs Epsom salt for Fish Tank (Things to know)

Aquarium salt vs Epsom salt for Fish Tank (Things to know)

Aquarium salt and Epsom salt are two common salts often used for different purposes in the aquarium hobby.

Aquarium salt (sodium chloride) is a general-purpose salt usable to make water more alkaline and help with fish health. Meanwhile, Epsom salt (magnesium sulfate) is a type of mineral salt used to improve the hardness of freshwater for some fish.

In this blog post, we will take a closer look at the differences between aquarium salt and Epsom salt, discussing when it is appropriate to use each one.

What is Aquarium salt?

Aquarium salt is a type of salt formulated for use in aquariums. It is made from evaporated seawater and contains sodium chloride that is beneficial to fish and other aquatic creatures. Aquarium salt can be used to help maintain proper water chemistry, improve gill function, and reduce stress in fish.

It is also sometimes used as a treatment for sick or injured fish.

Aquarium owners add this sodium chloride salt to help with some different issues, including:

  • Reducing stress in fish
  • Reducing the spread of disease
  • Helping to remove toxins from the water
  • Increasing oxygen levels in the water

When using aquarium salt, make sure you follow the directions carefully. Too much salt can be harmful to fish, so it is important only to use the recommended amount. Aquarium salt can be added to the water either directly or using a filter system.

What is Epsom salt?

what is aquarium salt

Epsom salt is a mineral compound consisting of sulfate and magnesium. It’s often used in gardening and farming to help plants grow more vigorously.

Epsom salt is sometimes added to the water in the aquarium hobby to create a more natural environment for fish and other aquatic creatures.

Epsom salt is a naturally occurring mineral compound of magnesium sulfate. It has many uses, one of which is a stress-reliever for aquarium fish.

Aquarium fish are often stressed by the changes in their environment, such as when their tank is cleaned or new fish are added. The sulfates in Epsom salt can help to detoxify the water, making it healthier for your fish.

The magnesium in Epsom salt can also help to promote plant growth.

Aquarium salt vs Epsom salt: Which one should you use?

  • Price: Aquarium salt is cheaper
  • Composition: Aquarium salt is made up of sodium chloride, while Epsom salt is magnesium sulfate.
  • Side effects: If aquarium salt is used in too high of a concentration, it can be harmful to fish. Epsom salt can also be harmful if used in too high a concentration.
  • Effectiveness: Aquarium salt effectively raises the specific gravity and helps with the molting process in invertebrates. Epsom salt is effective as a laxative and to soothe sore muscles, but it is not as effective as a fertilizer for plants.
  • Cure parasites: Aquarium salt
  • Safe for use with aquarium plants: Epsom salt
  • Adjust pH level and hardness level of tank water: Epsom salt
  • Heals fish injuries: Aquarium salt
  • Help treat dropsy: Epsom salt
  • Help with the gill function: Aquarium salt
  • Decrease the absorption of nitrates: Aquarium salt

FAQs Aquarium salt vs Epsom salt

What is a good alternative to Epsom salt for fish?

Generally, aquarium salt can be a good alternative to Epsom salt for certain applications such as improving gill function and reducing fish stress. However, it’s not a direct replacement as it does not possess the same attributes like adjusting pH levels and hardness of water.

Can I use sea salt instead of aquarium salt?

Sea salt can be used in marine aquariums but is not a direct substitute for aquarium salt in freshwater tanks. Sea salt contains other minerals and trace elements that might not be beneficial for freshwater fish.

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Can I use table salt instead of aquarium salt?

It’s not advisable to use table salt as it often contains additives, like anti-caking agents and iodine, that can be harmful to fish.

How many times can you reuse Epsom salt water?

It is not recommended to reuse Epsom salt water as it may have lost its beneficial properties and could harbor harmful substances after the first use.

How much Epsom salt to add to water for the fish tank?

This greatly depends on the reason for its use, but generally, the guideline is about 1-3 teaspoons per 5 gallons of water. Always ensure to dissolve the Epsom salt thoroughly before adding it to the tank.

Can too much aquarium salt kill fish?

Yes, excessive aquarium salt can harm and potentially kill fish. It is important to follow the recommended dosages and always gradually introduce any changes to the water.

Is aquarium salt safe for plants?

Most aquarium plants can tolerate small amounts of aquarium salt. However, high concentrations can cause harm, so it’s best to use it sparingly if you have a planted tank.

Is aquarium salt safe for shrimp?

Yes, but in small amounts. Many shrimp species are sensitive to salinity changes, so you should use a lower dosage than you would for fish.

Why did my Epsom salt get hard?

Epsom salt can become hard or clump together when exposed to moisture. This does not affect its effectiveness but can make it harder to measure accurately.

How often to add salt to freshwater aquarium?

Salt should not be used regularly in a freshwater aquarium. It is typically only added during a fish illness or to help new fish acclimate to the tank. Following the manufacturer’s instructions on the packaging for the appropriate dosage and frequency is recommended.


Epsom salt is a versatile product that can be used for many purposes, including as an aquarium salt. However, it is essential to remember that Epsom salt is not the same as regular aquarium salt and, therefore, cannot be used interchangeably.

Aquarium salt is specifically designed for use in freshwater aquariums, while Epsom salt can increase the hardness and adjust pH level, thus good for aquarium plants.

Aquarium salt is also generally more expensive than Epsom salt. While both products have their benefits, it is essential to choose the right one for your needs to get the most out of it.

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