Can large water changes kill a nitrogen cycle?

[Velice]

Hello!

I've read people saying that big water changes can kill your cycle and I would like to know if this is true and how it could happen. Am I at risk of crashing my cycle?

I have a 20g long tank with a canister filter and a sand bottom. I do weekly water changes of about 60-75% with the same spring water every time. I also shut off the valves to my canister filter to keep it full of water. I also started with a fish less cycle and a bare bottom tank, so I know there is a bacteria colony in my filter.

I just dont get how my cycle would crash if I'm only removing water. Don't the bacteria live on surfaces?

 

[Kaini]

The bacteria live in your filter media and on surfaces yes, so water changes won't crash your cycle. That's a myth.

 

[auntiejude]

You can kill your cycle in various ways - heat, water chemistry, chlorine, scrub the filter with bleach etc, but not with a big water change.

But I have a couple of questions:
Why do you use spring water? That must get expensive (unless you have a spring or well in your back yard)
Are you checking your water hardness? Some springs and wells have insufficient calcium and other minerals to keep an axie healthy.
Why are you doing such large water changes? If your tank is cycled you shouldn't need to more than 20-30%.

 

[layna]

Its partially true i that if the filter dries out or loses too much oxygen then it can crash your cycle, but as long as your quick it will be fine