Goldfish Tank Water Change

There is no questioning on the benefits of a tank water change and how it ensures the health of all the living things in your aquarium. There is however much debate among goldfish owners about how much water should be changed during these routine water change and what makes for the best care. In general, there are three basic practices of tank water changing: only replacing evaporated water, a percentage water change and an entire tank water change.

The first practice is not recommended and should be avoided. When water evaporates and lowers the water level in your goldfish’s aquarium or pond, it leaves behind the heavier pollutants. If all you do is replace the evaporated water, over time these pollutants can make your water denser and build to unhealthy levels. To explain this effect more clearly, notice the water line marks on the sides of your aquarium glass. Those lines are the remnants of what is left behind when your tank water evaporates.
Air Bubbles in Water

The next two methods of a water change are both acceptable practices but not without some debate.

  • The main argument in opposition of a complete or large percentage water change is that you should not change all the water in your tank in one cleaning because it will change the chemistry of the water too much and will stress or kill your fish.
  • The main argument in favor of a large change is that you don’t eliminate all the waste in your goldfish tank with a partial water change and over time the waste levels can build to unhealthy levels.

Both schools of thought are correct; both can cause problems for your goldfish and both stress the importance of having fresh clean water in your goldfish aquarium – So what do you do? Typically, most advice found on the internet says to change at least 20-30% and to never change all of your goldfish tank water during routine maintenance. If you do 20-30% water changes your waste levels will build up but it won’t likely kill your goldfish. They would of course be happier with a larger water change so if you are feeling guilty, up your tank water change to 50-75%. This will eliminate much more waste and by leaving some water in goldfish aquarium, will not drastically change the chemistry of the water.


5 comments on “2 Methods for Changing Your Goldfish Tank Water

  1. Hi I have a 55 gallon tank with three medium gold fish and one zebra danio.
    I have notice that my three gold fish are not very active and are mostly on the bottom.
    I went to a pet store for a test water,they told me that the nitrates are very high.
    They recommended me to do a 30%of water change once a week.
    I did a water chance yesterday but they are still not that active.
    Do I need to do Another water chance,need help!!
    I don’t want my fish to die.

  2. Hi, when I change my tank water I take it off the bottom with a pump, that way it gets more of the waste and what not. Just a thought ^^

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