Exactly what type algae do you have?... Fuzz balls, are they grayish tufts?
Here is a site with some pics to help ID yours...
http://www.floridadriftwood.com/alga...ification.html
The first thing I see is that your N03 levels are a little high, I would try decreasing them to around 10ppm.
The second thing is to up your lighting to at least 10 hours daily. Most people run their daily lighting from 10-12 hours. Anything below 10 hours a day causes the plants not to photosynthesize as they should.
If your PH/KH readings are correct then your C02 is at 30ppm which is where it should be.
Other than that knowing the ferts you are using, the amounts and maintenance schedule would help.