How to Treat Well Water for Aquarium – Make it Safe

If your water source is well water for your aquarium, are you going to need to buy tons of bottles of water just to fill your tank or can you simply treat it?  This is a dilemma for many fish owners are facing.  I will explain how to treat well water so that it can safely be used in your tank no matter what the size of the tank.

There are steps that you need to take to purify well water. Well water contains many minerals and other elements that can affect the health of fish.  It might seem like a better choice than city water that has chemicals added to it, but this is just not so.  The first step is to test your water to see if it is already suitable for your fish aquarium.

Testing the Well Water to See If It Is Ok for Your Fish

  1. If you have a softener for your well water, you will need to turn it off when you are putting aside water for your fish tank.  Softened water has had the calcium that hardens water replaced by sodium.  High levels of sodium can be detrimental to some species of fish.  To turn off a softener, you can simply turn off the valves that connect to the water supply. Now the hardened well water will not be softened.
  2. It is best to test for several chemicals that might be in your well water.  The first would be ammonia. You might think that it not possible to have ammonia show up in well water but it can happen.  Some fertilizers contain this chemical and the run-off from farmland can seep into well water. I recommend the test kit by API for ammonia, click here for pricing on Amazon.
  3. Well water can have a ph level that is higher or lower than the ph value of the tank of water in the fish store where you had purchased your fish.  It is prudent to always ask the employee in a fish shop of the ph level of their tanks so that you can try to match it. There is no need to test it daily, once a month would be fine.  Always test it if there are fish that have died or that appear to be ill.  I recommend that you use the ph test strips by Med Lab Diagnostics (click to view pricing on Amazon).
  4. Nitrate can also be found in well water since it is has been known to leak into wells that are within or close to an agricultural area.  I recommend the Salifert Nitrate test kit that is found on Amazon that is designed for aquariums. You do not have to test often for nitrate. Once a month testing is fine and also during times when you have young fish since they are sensitive to nitrate.

How to Treat the Well Water for Your Tank

With well water,  after you have tested it using the above methods, you should be good to go.  One good aspect of using well water is that you do not have to remove chlorine that is found in tap water from a city.

If you notice that your well water is cloudy, it is best to wait until the sediments have settled down in your well so that the water that you use is not cloudy due to sentiments.

For well water that has a high pH level, add peat moss to lower the pH.  add one teaspoon of baking soda for every 10 gallons of water if the pH is too high.  After doing so, retest the pH level until it is at the correct level.

Method for Treating Well Water for a Betta Aquarium

Many people love betta fish because they are available in countless colors and numerous tail shapes. You do need to treat your well water if you are planning on adding betta fish to it.

Just as with well water for the average tank, you need to lower the pH level if it is too high by adding baking soda.  As mentioned above, check with the store where you had purchased the fist to see what the pH was in the store tank. On average a pH of 6.5-7.5 is fine for betta fish.

You should also wait until the water temperature is at room temperature.  It might be too low initially since it is coming from a well. It takes about 24 hours for the temperature to stabilize.

Besides the above steps for a betta tank or a normal tank, you should consider conditioning the well water that will be used in a tank.

Ways to Condition the Water After You Have Purified the Well Water in Your Tank

Conditioning well water will ensure that heavy metals are at an acceptable level.  Some feel that heavy metals can cause sudden death in fish, so reducing the metal levels is also advisable for your well water for tanks. One product that I recommend is Seachem Prime Conditioner (click to see Pricing on Amazon).  It is a detoxifier that removes heavy metals from water.

Pros and Cons of Using Well Water in Your Tank


  1. Using well water is a simple solution for your fish tanks if you are not connected to a water supply service.  You could purchase water in large quantities at a large outlet like Costco, but that is not terribly convenient and this option is not a free one.
  2. Another benefit is that you do not have to dechlorinate well water.  Most tap water has chlorine added to it as a health benefit and it is very toxic to fish.  There are a lot of products out that you can purchase to remove chlorine but one less step to worry about would be nice.


  1. It can be cloudy if there is a storm.  You will need to wait until the cloudiness has disappeared before even starting to treat if for your tanks.
  2. If you live near a farm, there is a chance that elements that are contained in fertilizer have seeped into your well water.  This toxicity will have to be removed from the water before adding it to a fish tank.

If You Use City Tap Water Instead of Well Water, is it Safer for Fish?

Using water directly from the tap for your fish can be dangerous for your fish. Most city water has been chlorinated. Chlorinate can quickly kill certain types of fish.  Even a simple tiny tank for your goldfish should be treated before you add your fish.

Chlorine in Tap Water can Damage Fish Quickly

You may feel that you could get away with not removing the chloride in tap water if you have hardy fish, think again.  Even the strongest fish will not be able to survive long in chlorinated water. It affects their gills. The tissue in the gills burns.  Also, chlorine can enter into the bloodstream and affect vital organs.

To remove the chlorine from tap water, you need to add a dechlorination agent. I recommend the Aqueon conditioner, click to see pricing on Amazon.  It neutralizes chloramines and chlorine making your tap water.

You need to cycle the tap water even after removing the chlorine

Cycling is not just simply letting your water set in a tank for a few days.  You need to introduce nitrifying bacteria to the tank of water.  This can be done in a few ways:

  1. adding a small portion of gravel
  2. stocking your aquarium slowly with fish, not all of the fish at the same time ( do not overfeed these fish, for the time being, test the water for traces of ammonia and nitrate, and when the water is free of ammonia and nitrate, introduce the rest of your fish.

In Conclusion

It is totally OK to use well water for your tank as long as you test it to ensure that the quality is not going to harm your fish.  Even though you are able to drink it,  fish are more sensitive to minerals that might be in your well water.  It is best to be prudent and to show some patience with your tank water.

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