ive been following the instructions to the letter and my tetras do seem alot happier, and as ive mention in previous threads, there colors have exploded, they have there blue tint in the fins, there blue stripe is amazing!so i must be doing something correct? after each water change they do seem to be perky-er , one even plays in the water as its being returned by my make shift siphon lol. i usually open the flap on the lid, poke the hose through and place it behind the filer, whether that be taking water out, or putting the water back in. most of the time they dont realize im doing it so i know im not directly causing them stress by the ACTUAL change, just maybe by the change in the water itself.