ok so when i do a 30% water change out of my 25 gal tank. when
putting the water back in to the tank do i take all the water pour it in then add the conditioner or add conditioner before putting the water in?

i always add the declorinator first then the water. haven't had any probs doing that way yet

thanks

The chlorine in water kills the good bacteria in filters so you need to add it before adding the fresh water

what is the best one 2 buy and do you stick with the same one all the time

I think all of them work. I have never heard of any brands having a reputation of not working or not being recommended

I personally use the stuff sold for ponds, its the same except its much more concentrated (the one i use uses 2.5ml for 40g) and works out loads cheaper than the stuff sold for tanks

i also use the same brand all the time(top fin) i think the only thing to watch for is that it also removes chloramine and heavy metals as well as chlorine