How to Soften Aquarium Water

When adding water to an aquarium, it’s not as simple as just putting the tank under the faucet and filling it up. Aquarium water needs to specifically suit the fish inside otherwise they may not be able to survive. 

The kind of water you add to your aquarium will determine how healthy your fish will be and needs to be carefully monitored. It’s not just a case of regularly cleaning out the aquarium, you need to consider what exactly is in the water you are adding to the aquarium.

One thing to consider is how soft or hard the water is. This might sound strange and, unless you have faint memories of your high school chemistry lessons, are probably wondering how water can be either hard or soft.

Water hardness might sound strange, but it’s important you use the correct water for your fish. Even if your fish seem fine, they may not be. Just because the water isn’t killing them, that doesn’t mean that they are healthy. 

So, first of all, let’s get into what exactly is meant by “hard” and “soft” water.

Hard Water

Although we consider water to be a very neutral drink, it is actually full of many things. Water “hardness” is determined by how much calcium and magnesium it contains.

The higher the presence of these minerals, the harder the water. You can tell if your water is hard as it won’t produce much lather and, in areas with very hard water, it may leave a residue. 

Soft Water

Soft water, in contrast, contains very little calcium and magnesium and instead usually has higher levels of sodium. You can tell if your water is soft as it produces a lather when you wash your hands with soap.

Water Hardness and Aquariums

The hardness of the water in your aquarium is important as your fish’s environment should replicate its natural habitat as much as possible.

So, what do you do if the water in your local area is too hard for your fish to survive in? Well, don’t worry, you can easily soften the water in your aquarium.

One way to soften the water in your aquarium is by simply adding a water softener. Water softeners can be found in most pet shops and are relatively affordable. But there are also plenty of natural ways of reducing the hardness of aquarium water.

As already mentioned, your fish should be living in an environment that is as close to its natural habitat as possible. So, if your water needs softening, here are a few different ways of ensuring your fish are in the perfect habitat.

1. Water Softening Pillows

Water softening pillows can be installed in the filter of your aquarium so that it gradually mixes in with the water, reducing its hardness. Water softening pillows filter in sodium ions which replace the calcium and magnesium found in hard water. This option is best for small tanks.

2. Peat Moss/Sphagnum Moss

Another way of softening hard water is to use peat moss (also known as sphagnum moss). Similarly to the water softening pillows, granules of peat moss can be added to your aquarium filter so that the water passes through the peat moss. The moss then absorbs the minerals and releases tannic and humic acids. 

Peat moss is relatively cheap to buy, but make sure that it is untreated. Some peat moss is treated with fungicides which you don’t want. 

This sort of filtration most closely resembles the waters of rainforest rivers, such as the Amazon. 

This moss can also be sprinkled across the bottom of the tank and covered in a substrate such as soil, sand, or gravel. This will help to prevent pockets of low oxygen from appearing. These pockets can cause bacteria to grow that can pollute aquarium water.

3. Rainwater

Rainwater is a cheap and eco-friendly way to soften the water in your aquarium. You can easily collect rainwater and simply add it to the tank. This is only a good option if you live in a rural area, however, as the rainwater needs to be clean. Polluted water will obviously not be good for your fish, even if you use a filter.

If you live in a city or a highly industrialized area, then your water will likely be too polluted to use. But, if you live in an area where you can trust the quality of the rainwater, then this is the easiest option for softening aquarium water.

4. Driftwood

Driftwood is another eco-friendly and economical way to soften aquarium water. Due to the high levels of salt in the ocean, driftwood is full of sodium which will soften the water. Simply head down to the nearest beach and pick some up.

Again, this needs to be clean driftwood, so make sure you clean it once you get it home. You can scrub the driftwood or even boil it to make sure it’s free from anything that might harm the fish or discolor the water.

Don’t Forget...

Now you know all of the best ways to soften the water in your aquarium, but don’t forget that too much of anything is bad. If the water becomes too soft, then this can also be bad for your fish.

Make sure you keep the water balanced and regularly clean out the tank and change the water. Also, remember to change the filter and replace anything extra you might have added to the filter.

To find out if your water is hard or soft, mix some washing up soap in a water bottle and shake it well. If the water is clear and has lots of foam on top then it is soft. If it is a milky color and only has a thin layer or a few bubbles on top, then it’s hard. There are, of course, variances and some areas have harder water than others. But, as a general rule, clear water is the softest and milky water is hardest.