Whatever light that tank has change it for a 24W Osram 865 if you can put one in. Cut back the lights time and get a timer as Mikaila31 sugested, that way your lights always go on and of then they should.
The blue light... I'm not sure what it is but it might help the algae, some lights actually help algae grow.
For the algae problem you can do one of 3 things:
1)Blackout, kills them all and for good, no fish will suffer, just feed them well before you do it, i kept my fish without feedign them for longer than that and there was not a problem, even humans, dogs, cats, etc. can go that long without food. In the wild nobody feeds the fish, they eat when they can if they can.
2)Buy a aquarium uv sterilizer, will solve your problem and if there is any comeback you can always use it again.
3)Use the redfield ratio that is explained here: http://www.xs4all.nl/~buddendo/aquarium/redfield_eng.htm
Those 3 methods all work and they were posted from easy to hard.