Water changes are a key part of proper goldfish care. But what is involved in changing goldfish water?
Following the correct process can be the difference between keeping your fish strong and healthy in water that is perfectly suited to its needs, and keeping your fish in poor quality water that is hazardous to its health.
For example, goldfish cannot live healthily in untreated tap water.
In this post, we explain how often you should do a water change, how much water to change each time, and tell you some of the most common mistakes people make when changing goldfish water.
Changing goldfish water
How often should you change your goldfish’s water?
Generally speaking, you should change some of your goldfish’s tank water once per week.
We say “generally speaking”, because you will need to do more regular water changes in some situations. For example, if your tank was not properly cycled before you added your fish, then you may need to change some tank water as often as daily, in order to keep ammonia levels under control. You should regularly use a test kit that measures ammonia (such as this one) and one that measures nitrite and nitrate (such as this one) to keep an eye on your goldfish tank’s water parameters. Change the water more often if you see spikes in ammonia or nitrite (see our post on cycling your tank).
How much water should you change each time?
You may have noticed that we said to change “some of” your goldfish’s tank water each week. You should not change all of the water at once! In a properly cycled tank, we suggest a weekly water change of around a third of your goldfish tank’s water.
How to do a water change
If you’re wondering how to actually go about changing your goldfish’s tank water then simply follow these 10 easy steps:
- Buy an aquarium vacuum (also known as a siphon or hose).
- Get a bucket.
- Turn off any equipment, such as your filter or air pump.
- Stick one end of the vacuum into the bucket and the other into the gravel at the bottom of your tank. Switch on the vaccum (or manually pump if necessary) to remove the water from the tank and transfer it to the bucket. This removes both water and waste from your tank at the same time.
- Keep vacuuming/pumping, while moving the hose around your tank to different areas of gravel, until around a third of your tank water has been removed (you may have to empty the bucket once or twice).
- Remove your filter and place it into the bucket of tank water – note: tank water, NOT tap water – gently squeeze out your filter sponges to remove any gunk that may be blocking your filter.
- Put your filter sponges back into your filter and re-install the filter in the tank.
- Wash any other equipment or decorations in the same way – in tank water, not tap water.
- Fill your bucket with tap water and – before adding it to your tank – treat the tap water with a product such as Seachem Prime. Follow the instructions on the bottle and do this for every bucket of tap water that you use.
- Gently and slowly pour the treated tap water into your tank. You should do this one bucket at a time and very slowly. Otherwise, the change in water condition and temperature may shock your fish.
The biggest water change mistakes goldfish keepers make
There are three major mistakes that new goldfish keepers often make when doing a water change:
- Washing their tank equipment and decorations in tap water – your filter sponges, gravel and decorations are where the good bacteria in your tank live! You should NEVER wash your filter, filter sponges, gravel or decorations in tap water, as it will kill this good bacteria! Instead, every time you do a water change, remove a bucket of tank water and use that to clean your tank’s equipment and decorations.
- Not treating tap water before adding it to the tank – water contains chemicals that can harm the colony of good bacteria in your tank. You should therefore use a product such as Seachem Prime whenever you do a water change. Prime treats your tap water and removes chemicals that could harm your fish or bacteria colony, such as chlorine, so that the water is safe to be added to your tank. Never keep your goldfish in untreated tap water.
- Adding water too quickly – adding tap water too quickly or when it is at a very different temperature to your tank water can shock your fish. This can make your goldfish stressed, which lowers its immune system and increases the chance of it getting ill.
Perform water changes properly with: