My water test fine for everything; do i still need to do water changes?

Question

I have a 50 gallon with neon tetras; zebra danios; and guppies. My water test adequately every time I check. Is it still necessary to do water changes if everythings testing fine?

If so; why?

I have many live plants and have not done a water change in quite some time (I moved and my siphon is still in storage) I have been testing my water frequently and nothing has changed. Can I wait until a slight change in something to do a water change? My cousin has a 50 gallon with a great filter; live plants; etc (just like mine) he never does water changes and his fish are extremely healthy.

Answer 1

It's because you do water changes that your water tests are good!

Eventually the ammonia and nitrite will all be converted to nitrate by bacteria, but unless you have lots of plats (or algae) nothing removes the nitrate. It's less toxic than the other two compounds, but if it gets high enough, the fish can get nitrate poisoning. Water changes are the best way to keep this from happening.

Not only should you do water changes to take chemicals out of the water, there are some in the replacement water (calcium, magnesium) that the fish and bacteria in the tank use, so water changes one way these are provided.

Answer 2

its recommended to do a 10% water changes every week, if you have a good filter, you can do a 25% water change every 2 weeks.