How To Soften Aquarium Water. 7 Safest And Most Effective Methods

About 85% of the United States has hard water, and it’s likely that that includes your home. Hard water refers to a high content of dissolved minerals. Soft water contains very few dissolved minerals.

Some fish thrive in hard water, while others need soft water. If a fish that needs soft water lives in hard water, it will become stressed. This can lead to disease and death.

It’s important to know if your home has hard water and whether your fish needs hard or soft water.

But don’t worry if you have the wrong kind of water. There are ways to soften aquarium water. Keep reading to find out the most effective methods.

How Do You Measure Hard Water?

You can measure your water’s hardness in a couple of ways. KH refers to carbonate hardness. It measures the bicarbonate and carbonate ions in the water. GH refers to general hardness and measures the calcium and magnesium in the water.

These are common terms used in the fishkeeping world, and you’re likely to see them at some point. Yet, you’re more likely to measure hardness using Parts Per Million (PPM) or Degrees Of Hardness (dH).

Water is soft when it is between 0-100 ppm or 0-6 dH.

Water is hard when it is between 101-440 ppm or 6-25 dH.

Water is very hard when it is >450 ppm or >30 dH.

Luckily, it’s very easy to tell if your water is hard or soft. You can buy a testing kit online or at your local pet store.

#1 Soften Your Water With Chemicals

Using chemicals is one of the most popular ways to reduce the hardness of your water. It’s fast and effective, and it doesn’t need a lot of effort. Seachem’s Equilibrium and Alkaline Buffer work great for this.

It might sound bad to use chemicals in your tank, and that’s why many people don’t like to use them. But don’t worry, these chemicals are designed to be safe for your fish.

But, the chemicals could harm your plants or invertebrates. So, you should check the ingredients to make sure they’re safe for everything living in your tank.

Chemical softeners generally work quickly which is why so many people love them. The problem with chemicals is that they don’t last very long. Eventually, they’ll lose their effectiveness.

So, to keep your water hardness down, you’ll need to dose your tank regularly. Most people dose their tank after each water change to keep the water softness where it needs to be.

So, as long as you can remember to keep up with dosing, this can be an effective method.

#2 Use A Water Softening Pillow

This is another way to lower the hardness of your water through chemicals. These pillows come coated in an ionized resin. The resin binds to the heavy metal ions and minerals found in the water. The resin then removes the ions and minerals.

You should place one of these pillows inside the filter. This allows the pillow to work alongside the filter, catching the ions and minerals. You can then replace the pillow once a month when you replace your filter cartridge.

The nice thing about these pillows is that they soften water over time. The softening process doesn’t happen as quickly as it does with liquid chemicals. This makes the process easier on your fish and prevents them from going into shock.

#3 Use A Reverse Osmosis Filter

Another artificial option is to equip your water system with a reverse osmosis (RO) filter.

Your regular water filters through a semi-permeable membrane. The water pushes through the membrane at high pressure. This allows the filter to catch all impurities.

RO filtered water is the best kind of water you can use for your aquarium. RO filters remove dangerous and even deadly contaminants from the water. Some examples include nitrate, perchlorate, arsenic, and hexavalent chromium.

It even removes bacteria and viruses such as campylobacter, E. coli, and salmonella. As you can imagine, this is wonderful to have for your aquarium. Pure, filtered water helps ensure that your fish never develop preventable illnesses.

The downside to using an RO filter is that it can be quite expensive. Even the smallest filters cost a pretty penny, and they only produce a few gallons of RO-filtered water at a time. This is no problem if you only have a single, small aquarium. But if you have a large aquarium or many aquariums, it can become difficult.

If you’re set on using RO water for your aquarium, you could always buy a large expensive filter. But, there are better options.

Some pet stores that specialize in fish will sell RO water by the gallon. You can fill up buckets to take home with you. The water is generally cheap, so this method won’t break the bank.

Another option is to install a small filter under your sink and stock up throughout the week. This is an effective and easy method as long as you have the space.

Simply save empty milk jugs, clean them out, and fill them up with water every day. If you do this every day, you will have enough filtered water stored up by cleaning time.

#4 Add Some Distilled Water To Your Tank

Distilled water is like RO filtered water. The water is completely pure but contains no minerals. This is good for lowering the hardness of our water. Yet, it’s not good for your fish to miss the nutrients it needs.

To fix this problem, only use a small amount of distilled water. Try filling your aquarium with about 75% of your regular water and 25% of distilled water. The distilled water will dilute the regular water enough that it softens. But, it will leave behind enough of the minerals that your fish need.

If 25% distilled water isn’t enough, you can try using more. Add little by little until you reach your desired harness. Keep testing your water until you’ve reached the level of hardness that you need.

#5 Include Peat Moss In Your Aquarium

If you prefer a more natural method, you can try adding peat moss to your substrate or filter. Peat moss catches the minerals in the water. It binds them together in a process called “chelation”. This reduces the mineral content of the water, thus reducing the hardness of the water.

Bear in mind that the tannins in peat moss are likely to turn your water a light brown. This is completely harmless, but some people don’t like how it looks in their tank. Peat moss will also lower the pH of your water.

Many people will mix the moss in with their substrate. It gives the aquarium a lovely, natural look. Others will stick it in their filter so that it’s hidden.

Another method is to pre-treat the water. Add the peat moss to a bucket with water a few days before it’s time for a water change. The moss will collect the minerals, and after a couple of days, you can remove the moss. Then, add the new, pure water to your aquarium.

#6 Add Driftwood To Your Aquarium

Driftwood is a great natural decoration. But, it can also reduce the hardness of your water. For driftwood to be effective, it can’t be boiled or treated with chemicals. You must choose 100% natural driftwood.

Keep in mind, though, that driftwood also releases tannins.

Driftwood will also lower the pH of your aquarium’s water. If your pH is too high, then this is a great thing. But, if it lowers it too much, you may need to take steps to raise the pH back up.

#7 Add Indian Almond Leaves To Your Aquarium

Adding Indian Almond leaves is another natural method. Like driftwood, these leaves contain tannins that will turn your water a light brown. But, these tannins also reduce the water hardness in your tank.

Better yet, Indian Almond leaves help your fish stay healthy. It boosts their immune system and helps them stave off illness.

You can add the leaves straight to the tank. Be sure to remove them before they begin to break down or they may cause an ammonia spike. Another option is to boil the leaves to create a natural tea. After boiling, throw the leaves away and save the water. Once the water cools to room temperature, you can pour it right into the aquarium.


We hope that you enjoyed this list and found it useful. So many people find water hardness to be intimidating, but it’s so important.

Try your best to provide your fish with the right level of hardness. It will decrease their stress, boost their immune system, and give them with happier lives.

If you found this list helpful, consider sharing it with other fish keepers in your life.

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