water treatment additive based on tank size or amount of water added during water change

[finfayce]

I'm with @Essjay and @Byron (and others). If you're de-chlorinating in a bucket or barrel then you typically only need the exact amount for the water to be processed. Refilling directly in the tank (e.g. Python like) is questionable. Manufacturers recommend treating for the entire tank volume. Many hobbyists have reported success directly refilling using only the amount of conditioner for the water being added to the tank.

A fellow club member recently told me that he's on a municipal (chlorinated) water supply, does 20% water changes, and uses NO conditioner at all!!!
A while back, our club president did a water change on several tanks in his fishroom using the routine amount of conditioner, but by the next day, lost all the fish in the affected tanks (suspect that excess chlorine was in play due to water main issues).

So it seems to me it's like an unpredictable crap shoot. Manufacturers recommend treating for the entire volume and although we might think they're just covering their backsides while trying to sell more product, we might also conclude that they've done tests that suggested or determined that the product was not effective unless the the entire tank volume was treated.
It seems to me that unless we suspect some problem with the conditioner, treating for the entire volume, although perhaps conservative, just may be safer for your fish.

Footnote: I have well water and although in the past I've had to deal with high nitrates, ammonia, and excess CO2, I'm glad I don't have to deal with and condition for chlorine/chloramine!

thanks for your answer. i did by the bucket amount for my shrimp. they’re so tiny, but
i ‘ve read they are hardy. just don’t want to take a chance.

 

[Colin_T]

thanks for your answer. I did by the bucket amount for my shrimp. they’re so tiny, but I‘ve read they are hardy. just don’t want to take a chance.

Nothing is hardy when it comes to chlorine/ chloramine poisoning

 

[finfayce]

Nothing is hardy when it comes to chlorine/ chloramine poisoning

 

[FishHobby99]

I follow the dosing instructions for the dechlorinator, often measuring concentrated products with a 1 ml syringe. This is squirted into the tap water before being pumped or bucketed to the tank.

 

[finfayce]

I follow the dosing instructions for the dechlorinator, often measuring concentrated products with a 1 ml syringe. This is squirted into the tap water before being pumped or bucketed to the tank.

thanks- i do that also. especially need to use that with smaller tanks v