Water conditioners not needed for <20% water changes?

[Il Pirata]

"The Bailey Brothers discovered that doing a partial water change by replacing 20% or less of the water in an aquarium, fish bowl, or pond with tap water containing chloramines is almost always safe. In fact a small amount of chloramines seemed to improve the health of the fish. Perhaps a small amount of chloramines reduces the number of pathogens in the water without harming the fish.

The small amount of un-neutralized chloramine will probably reduce the number of pathogens and may improve the water quality for fish.

But changing more than 20% of the water with water containing chloramines is risky to fish, even if a commercial Water Conditioner is added to the water."

What's your experience?

[tetrakid]

"The Bailey Brothers discovered that doing a partial water change by replacing 20% or less of the water in an aquarium, fish bowl, or pond with tap water containing chloramines is almost always safe. In fact a small amount of chloramines seemed to improve the health of the fish. Perhaps a small amount of chloramines reduces the number of pathogens in the water without harming the fish.

The small amount of un-neutralized chloramine will probably reduce the number of pathogens and may improve the water quality for fish.

But changing more than 20% of the water with water containing chloramines is risky to fish, even if a commercial Water Conditioner is added to the water."

What's your experience?

I fully agree with that idea and like it. The secret is in the concentration amount.

But my concern, though, is the effect of it on the bacteria on the bio media.
Unfortunately, there's no way to check the effect other than by trial and error.
It would be a pity to impair the integrity of the bacteria which we took so much pain to build up.

[Dscheng]

Agree with Tetrakid, even 10% i also don't risk at all.

[Urban Aquaria]

I guess it really all depends on how much chlorine/chloramine and heavy metals there are in the source tap water... and also how sensitive the beneficial bacteria and livestock are to those things.

Observations by other aquarium keepers online are based on their own country tap water conditions, which may be different from ours (theirs may be cleaner or more natural and don't contain as much chemicals or additives), so have to factor that in.

If a tank is well established with strong beneficial bacteria populations, a small percentage of untreated tap water would probably be less likely to destabilize the system, some people regularly do water changes with untreated tap water and find that its okay... so its suitable for their particular system and livestocks.

On the otherhand, there are those who do the same and then the tank becomes cloudy due to bacteria bloom or ammonia levels start spiking (which indicates the cycle is affected), or their livestock start to exhibit stress or deaths, then its a sign they have to treat the tap water for their setup.

[barmby]

In the past I wouldn't care much about 25% water change because the percentage is small. I think this is a personal question - the amount of care and tenderness to be given. I will do 25% water change with anti chlorine without blinking Have fun