cloudy water, but NOT a new tank

[tank-challenged]

10 gallon tank, with goldfish:

okay, so the water was clear as can be a few days ago... and i mistakenly did a pwc (with the gravel vacuum) and didn't pay attention and changed a good 50% of the water.

started getting cloudy -- did all the tests (ph, amm, nit) and all checked out as okay. so what's with the cloudiness? and what to do now?

[tbonem91]

how many goldfish and what kind? IMO more than 1 goldie per 10g is too many.

what are "fine" readings? NH3, NO2 = 0 and NO3 < 20 are ideal

what kind of filtration do you use? did you replace any filter media recently?

chances are, that the cloudiness is a bacteria bloom and will go away on its own - you likely killed off most of your bacteria population and it will take some time to re-establish itself. You might go through a mini cycle and if so, you will need to do small PWCs frequently to keep ammonia and nitrite readings < 0.5 ppm.

edit: did you vacuum the gravel or just use it to replace water? also, how often do you usually replace water and gravel vac?

[Fishyfanatic]

Changing 50% of the water will not cause a tank to be cloudy unless there is another problem. What color is the cloud?

[DepotFish]

Your tank is more than likely overloaded. How long has it been setup? Has it cycled? Overfeeding or switching foods can cause a bacteria bloom.

[Zagz]

I've had tanks get suddenly cloudy, usually because of needing water change or strangely enough, the other day one of my cats threw a tree leaf into one tank!

I would have to agree, goldfish need 10 gals per fish. I have goldies in an overstocked tank because I had to rescue them. I've given a few away to help but I run 2 large filters and do pwc's every 3 days. After we move they will be getting a 90 to themselves. The water in their tank can get very cloudy in a hurry when 3 days has gone by. I would guess overstocking is your cause of cloudy water.