How much should i panic

[Honey Badger 1]

I use a python water changer so I dose the tank before I add new water. If you use buckets then put the Prime in the bucket, add water, then pour it into the tank.

[BiGBlak]

I always add before I fill up also was just curious I felt I overreacted a bit. While I was panicking I read a bunch of people claim that they don't use water conditioner on anything less then a 50% water change is that a old rule ? I couldn't imagine feeling comfortable not adding some amount of prime no matter what amount of water I'm adding even when I'm topping my tank off.

[Dennis Bissett]

I always add before I fill up also was just curious I felt I overreacted a bit. While I was panicking I read a bunch of people claim that they don't use water conditioner on anything less then a 50% water change is that a old rule ? I couldn't imagine feeling comfortable not adding some amount of prime no matter what amount of water I'm adding even when I'm topping my tank off.

Hard to answer, all my changes are 50% or larger, I dose into the sump filter before adding on the large tank, and during refill on the smaller ones, and always dose for tank size regardless of water change amount

[Indian Woods Angels]

On a 20% water change it should have no serious effect.

Most water changes consist of adding a water treatment for sterilants to the tank, waiting several minutes and then adding water from the tap directly to the tank.

If we really examine this process we do still expose the fish to any chemicals that may be in the water prior to the chemical reaction taking place that neutralizes the chemicals. And so the fish are most likely exposed each time we do a water change to some chemicals that may burn the sensitive tissues on them.

If we waited for the treatment to disperse into the water a bit and then did our water addition in two stages so that the treatment were able to react it would be better for the fish. Add some water, maybe half back, wait 5 to 10 minutes for reaction and dispersement and then add the remainder.

On sensitive species such as rainbows, danios or other high oxygen fish that suffer greatly from burns to the gill tissues we should alter our methods to 2 30% water changes per week. This gives us a lesser chance at sterilant exposure damaging our fish.

If we have these sensitive species we could examine our process a bit to help keep them in fine health.

[Cermet]

You must use a de-chlorinator for all water changes, even very small ones. Those chlorine chemicals are very toxic to fish and inverts. BIGBlak, not using treatment for small W/C is utterly incorrect information.