Can you use Rainwater in Fish Tank

Can You Use Rainwater In Fish Tank?

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Fish tanks have become some kind of a phenomenal. There has been an ongoing debate whether it is safe to use rainwater in your fish tank. What’s more, there are a few different ideas that are floating around the internet. Whether you are looking to fill a new tank or looking to perform water change, you should ensure you use safe water.

So, can you use rainwater in a fish tank? Yes, you can use rainwater in your aquarium. However, you need to know certain facts before using the water. Know the type of fish you are keeping, and the hardness of the rainwater. You will be required to measure the general hardness and carbonate hardness. The two are associated and correlate with TDS. You will have to buffer and treat the water before using it.

This article will look at the subject deeply and offer you more insight. Read on to find out what kind of water you should use, how to condition water for your aquarium, and other related issues.

How to Properly Use Rainwater for Your Fish Tank

Though many are of the view that rainwater is safe, it may have some impurities especially if you live near a busy road, a power station, or a factory. What’s more, it may pick chemicals from water butt, gutters, and the roof.

Clay tile roofs and slate are a bit safe but you should avoid water coming from roofs that have asphalt, tar, and weatherproofing chemicals. If you are planning to use rainwater, ensure that your downpipes and gutters are clean. There are a lot of debris including tannic acid and ammonia that build up in them when you do not clean the gutters regularly.

Another precaution to take is adding tap water to the rainwater. Mixing rainwater and tap water in the appropriate ratio brings about the ideal water hardness that many fish survive in. However, if you want to use rainwater alone, you need to adjust it with appropriate pH and hardness level that is ideal for your fish to stay healthy. To be more specific, you have to add rift valley cichlid salt mix to attain hard alkaline water conditions or add Discuss Buffer to get soft, acidic conditions.

What Kind of Water should you use in a Fish Tank?

Having a home aquarium will provide you with hours of relaxation and fun. Studies show that those who spend some time watching fish in tanks have lower blood pressure and heart rates. However, you may not keep the fish for long if you do not take care of the aquarium in the right way. This includes the kind of food you feed them as well as the kind of water you use.

Below are some of the water sources for your aquarium.

1.Tap Water

One of the easiest ways to get water for your fish is using tap water. However, some of the water may contain asbestos or ammonia, which is harmful to some kind of fish. Another issue with tap water, especially the one from municipalities is that it may contain chlorine. Chlorine kills both the good and bad bacteria and it is harmful to fish.

Nonetheless, you should disinfect tap water to get rid of the bacteria and it will be good to use in your aquarium.

2.Reverse Osmosis (RO) Water

Reverse Osmosis water is the one that has undergone reverse osmosis filter. The process allows water through fine membranes that traps particles that allow clean water to go to the other side. Reverse osmosis is highly effective and is one of the best choices for aquariums.

3.Deionized (DI) Water

If you want to ensure that the water you use in your aquarium is free of chemical contaminants and minerals, deionized water is among the best choices. It is ineffective against bacteria but it is effective in filtration of some contaminants that even reverse osmosis cannot catch.


You can use rainwater for your aquarium if you cannot afford to bottled water or use tap water. However, most of the rainwater has low mineral content and PH can vary. What’s more, rainwater can also become polluted with contaminants found in the atmosphere. The water can also collect asbestos from shingles on rooftops. Thus, you will need to treat the water before using it.

How to Condition Water for your Aquarium

While it matters little the kind of water you use for your aquarium, you will have to condition it to ensure it is safe. When you condition your water, there are certain parameters you should consider including the following:

  • GH is a measure of the general hardness of water. It measures concentration of magnesium and calcium ions in water.
  • You should also check the KH, which is the measure of bicarbonates and carbonates in water. Low levels of bicarbonates decrease the ability of water’s ability to buffer the Ph.
  • You should also check for the power of hydrogen. Checking the concentration of hydronium will determine whether it is alkaline and acidic.

Ensure your tank has the right balance of good bacteria and minerals, which are free of the harmful substances. Moreover, you can buy a water conditioner that will help you remove chlorine from the tank. You can also add baking soda to increase bicarbonate levels.

If you are looking to add minerals to the aquarium, buy a remineralizer and add several drops of the remineralizing substance to the tank.

Different types of Aquariums in Terms of Water Used

There are different types of aquariums that you can put in your home. Here are some of the aquarium types.

1.Coldwater Aquariums

Most of the coldwater aquariums have some type of aerator and should be kept at room temperature. They are the most common types of aquariums in many homes. They are also popular because they are easy to maintain.

2.Freshwater Tropical Aquariums

The biggest difference between freshwater tropical aquariums and cold-water aquariums is the water temperature. It brings about concerns that include heating and maintaining temperature ranges since for freshwater tanks the temperature ranges from 72 to 84 degrees.

3.Marine (saltwater) Aquariums

Marine Aquariums offer the species of fish that freshwater tanks cannot. However, they require more effort to provide viable living conditions for saltwater fish. Most of the saltwater fish do not adapt well to variations in their ecosystem.

4.Brackish Aquariums

These kinds of aquariums are not common; experienced fish owners with in-depth knowledge about fish tend to use them.

Related Questions

What is the best Aquarium Size?

The size of the aquarium will depend on the number and type of fish you keep. For each inch of fish you keep, you will require one gallon of water.

Are Plastic tanks bad for fish?

When plastic is left in water for very long they may end up releasing potentially toxic chemicals. For this reason, you should avoid plastic fish tanks at all costs.

See Also:
Is Used Fish Tank Water Good for Plants?
How Do You Know if Your Algae Eater Is Dying?
Why Does Algae Grow in Fish Tanks?