Cloudy Tank

[vanderdraay]

woke up this morning to find my tank was so cloudy i couldnt see to the back of my tank its a juwel vision 450, ive got a fluval fx5 cleaning and do regular water changes, so i changed 250 litres straight away and cleaned my filters but the water is exactly the same 12 hours after i changed it, ive left the lights off and put a heavy sheet over the front to stop any light getting in .The tank isnt in direct sunlight and lights are only on for 10 - 12 hours a day sometimes less, has anyone had a problem like this before ? its the first time this has happened and i dont want to lose any fish any info would be very helpful

 

[Cazgar]

How long has the tank been running & have you added anything New?
I've had it a couple of times when I've done larger than usual water changes.
It could just be a bacterial bloom & should clear on it's own in a couple of days

 

[vanderdraay]

ive been running the tank for a year and half i introduced a small rotkiel on friday, i went through the normal procedures of introducing new fish as always, i only normally do around a 50 - 60 litre water change weekly but ive done a biggy this time after the shock of the cloudy tank