Re: mechanics of blackout

["S. Hieber" <shieber at yahoo_com>]

 Diana Brown said, in part:
> . . .but I came home to very overfed tanks (floating and
> sinking
> excess food in 3 of 4 tanks) and a new horrid almost clear greyish
> slime on
> everything in one tank. . . I vacuumed the gravel, rinsed the
> filter
> media, and did a 50% water change, and things looked better this
> morning,
> but still not good.  I would like to try a blackout, although if it's
> bacterial it may not be affected by the blackout....but maybe the
> thick
> black brushy algae will go away even if the greyish stuff doesn't.
> 
> So how do you do a blackout?
> 
> I put some plastic garbage bags over the tank, so they overlap it
> loosely,
> but did not tape or otherwise seal the edges (I don't want to
> suffocate my
> two goldfish in their now-slimy tank).  I have unplugged the lights. 
> Is
> that sufficient for a blackout?  . . .will even a few minutes of dim
light now and then spoil the
> effect of the blackout?

The effect of light is making energy available to the the plants (and
algae) and a few minutes worth couldn't possibly make or break the
effect.  But the experts will hopefully weigh in on this.

Basic problem is too much food and it's fouling the tank, right?  So
blackout or not, you might want to consider doing repeated water
changes until enough waste is removed that nitrite/nitrate levels will
remain at acceptable levels.  The water changes will also help prevent
the levels from climbing and remaining too high while this thing is
unresolved.  Algae might consume some of the nitrogen products, so a
blackout, by denying algae the energy for photosysnthesis, might
actually help white, clouding bacteria.

It's awful when a good tank suddenly goes bad, but at least you have a
good idea what went wrong.

Good luck,
Scott H.

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