Algae B-B-BOOM!

[Robert Marshall <w22ram@morgan.ucs.mun.ca>]

My second tank has been setup for a little over 2 weeks in my 50 gal.
tank.  The algae it so thick that the water is very foggy.  There is no
ammonia present, the ph is 6.4 and 40 ppm of hardness; temp 77.5 F .  I
understand that algae is normally a problem during the initial 6 months
but is their something that I can do to reduce the amount of algae?  I
don't want to rely on chemicals unless I can be asured that it won't
have any adversed effects - like many products such as ph down.  The
bottom consists of an inch of ground clay (a kitty litter - couldn't
obtain laterite here in Newfoundland) and silica sand which has been
throughly risened out.  Performed 15% water change today.

My tap water is naturally low at 6.4 because Newfoundland drinking water
flows from areas of bogs which contain peat.  Hardness is 2 ppm.  I know
my counter parts using r/o machines and distilled water are envious.
The difficultity that I am having is that I cannot obtain any apisto
fishes which makes me envious - can't have my cake and eat it too.  I
seen a web page in Edmonton and the U.S. but shipping is too expensive
for a University student, especially after purchasing a 50 gal. tank in
an area with no competiton.  Any suggestions?