Lost

I'm starting to get a little frustrated with the algae in my tank so i thought i'd post here and here someone can gimme some pointers.

I'll start with my tank setup:

size: 80 litres
plants: heavily planted with red green ludwigia, hygro polysperma, straight vallis, 1 amazon sword, 1 nymphaea stellata bulb, and the forground is covered with pygmy chain swords
substrate: tahitian moon sand mixed with JBL florapol (wish i hadn't mixed it with anything now since im doing EI).
C02: DIY - 15/20ppm, cant seem to push it any further, need to get a proper kit.
light: 72w PC's mirrored reflectors.

My tap water contains no NO3, ~5 ppm PO4, very little KH/GH. I started doing EI about 3 weeks ago and have been following tom barrs suggestions and adding 1/8 tsp KN03 every other day (very hard to measure tho). 4ml trace on the off days. I dont need to add any KH2PO4 as the PO4 from the tap water doesnt seem to shift. when i've tested for N03 towards the end of the week its been around 20ppm. I've also been adding KH to reach 4dkh, and GH to ~7dkh.

Now the problem...

fuss/hair algae has grown rapidly since starting EI and is now covering pretty much every leaf, especially those towards the surface and those that arent shadowed by anything. the algae is dark green in color. I did a 3 day black out last week as i was stating to get BGA, and so far that has gone, but this other stuff came back within a day of turning the lights back on.

My tank looks stunning from a distance, but as u get closer u discover the grim reality.

Would get greatfull of any help.