haze

["Roxanne Bittman" <rbittman at dfg_ca.gov>]

OK, I will weigh in on this, but I'll bet many will think this is wrong.
 Still, it's my experience, so, for what it's worth:
I have noticed a whitish haze as the harbinger of green water bloom. 
It only looks white in the beginning; once it gets going, it will look
nice and green.  The filter output does indeed push the organisms
against the front glass and it looks a little like smoke.
There are two ways to rid yourself of this and you have add to KNO3 at
the same time, since I belive Tom Barr is right that green water is
often indicative of a lack of Nitrogen.  (So, question I have is, does
that mean some types of green water are actually bluegreen algae since
they are the ones that do well in low N environments??).  

To get rid of the green water either use a diatom filter (such as the
System  1 Pressure filter) or a UV filter.  The latter is faster, but I
prefer the former 1) because I have one and 2) because it takes out the
organisms as well as cleaning the water.  The UV just kills them and
leaves them in the tank to decompose.
I would forget about chemicals, darkening the tank, changing water,
etc., though changing water once things start to clear is helpful.  I
keep adding traces, KNO3, PO4 after water changes and make no attempt to
"starve" the algae, which is what this is (HAH! starve algae, good
luck).
So, you may have to borrow that ole' UV again.  Sorry about that, but
be sure to check your NO3 levels; I will bet they are zero.
Roxanne Bittman