To many WC?

Not possible, no can do.

fresh water = stable water = healthy fish

Change to your hearts content.
 
WAIT WAIT WAIT!!

You can DO damage with a large water change in certain scenarios:

1- A tank which has had a very low mainteinance for a long time, ie, no periuodical water changes. This can lead to tremendous contaminated water being replaced by very clean water and causing problem to fish.

2- Using water with drastic different parameters (ph, kh, temp), which may shock the fishies.

However, it your tank has been properly maintained, and the water parameters of the new water is similar to old tank water, a large water change should not do any damage. Remeber, periocal water changes is the way to go.
 
Nice catch Pato.

Also, keep in mind water straight from the tap to the tank has more gasses in it than water that has been seasoned (left out a few hours to settle). Note the small bubbles that attach to the inside of a glass of stale water, that is the water degassing...

Fish left in a tank for large volume water changes with unseasoned water (like when people use a python water change system), say 70% + of the total volume of the tank, feel this pressure change and it CAN hurt your fish in some cases (anyone know more about this than I do? I'm not 100% here...) I think causing disorientation and swim bladder damage like symptoms... not sure I've never had it happen because I was taught not to.
 
I do 80-90% changes on all my discus tanks daily from the tap without degassing. Hmmmm doesn't hurt a dang thing. The only thing you need to do first is let a cup of water degas overnight, test before and after, if you have drastic changes, then you need to degas the water before putting it into the tank, if not dump in from the tap.

If your tanks are well maintained from the start, you can't do too many WCs period, degassing is unrelated to water changes it is something that may need to be done before adding new water, but if you need to degas before adding water to the tank that is simply the same as if you need to add a dechlorinator to your tap water before adding it. Once that step is done you start the water change, not before.

Frequent water changes with small or large volume amounts will keep healthier fish period.
 
NatakuTseng said:
I do 80-90% changes on all my discus tanks daily from the tap without degassing. Hmmmm doesn't hurt a dang thing. `

You do it daily, so your tank water is pretty much the same tap water.

I dream of a clean well water system, where I didn't need to use dechlorinator to set up a constant water change system.
 
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