You know how you are supposed to change 1/4 of your aquariums water every week. well i''ve been doing that. i first take out all the plants to wash them with water only. then i don't take out the fish i leave them in the aquarium. i disconnect the heater and filter. then with a vacuum, you know those that take the water out of your tank, well i take 1/4 of the water. then i replace the water with clean water but before i put it in, i first add the conditioner and ttheni put the water in. and almost every time i do that one fish or 2 dies. one time i tried taking the fish out before i clean the tank, because i thought i might be squishing them or something, but when i would put them back in the tank 2 or 3 will die. my aquarium is 10 gallons. and right now i changed the water as always without taking the fish out, and now ALL of my fish are dying. wwhydoes this happen? am i doing something wrong? they are dying right now all of them, what do i do. im tired of my fish dying. maybe im not supposed to change their water. PPLEASEHELP!