i recently changed some of the water in my tropical tank as i do quite regularly,however since doing this the water seems to be getting cloudier by the day!i woke up this morning to find 2 of my barbs dead!i have one other barb a plec a ruby shark and a couple of lamp eyes and relly dont wanna lose them,what can i do do i need a new filter?i have a fluval 1 filter which has been v.good up til now PLEASE HELP!