depending on what kind of filter you have, you may have thrown out most or all of the beneficial bacteria that serves as your biological filtration. bio filtration converts ammonia into nitrite, then nitrite into nitrates so that your fish don't die.
if you indeed got rid of most or all your beneficial bacteria, i would give the remaining fish to someone with space in their tank. they can take care of them while your tank cycles.
i recommend doing 25% water changes up to 3 times a day until you get ammonia/nitrite readings of 0, then add marineland bio-spira. if you do that, you shouldn't have to take the fish out.
I'm a newbie, but I've had my tank for around a month and a week, and i figured it's time to change the filter...well I did a partial water swap, then about 3 or 4 days later I bought new filter cartridges, put em in and the next day I saw some cloudiness, then sunday more, and now i've got dead cardinals and a really whiteish (if that's a word) cloudy tank. I know I did something horribly wrong, and I feel terrible. Any ideas?
