I did a very large water change today in my tank and now that i have been away from home all day i come home to discover that my piranhas have lost almost all color and are now whute and swimming at a slight angle and will not eat..When i changed my water did i take too much of the good bacteria out?. I also scrubbed the sides of my tank to remove the brown alage problem and then added proper amouts of tap water chemical and the proper amout of algae kill.......IS there anything i can do like put some of my old water back in "i kept it in a bucket"????? Help me please i dont wanna loose these guys.