giddygid, i know the advice is overwrought and almost banal now... but get your CO2 levels up and steady each day (25-30mg/l) and keep your plants well fed and well lit, and algae will be the least of your worries. With heavy BBA growth though, it could take 2-3 weeks for noticeable reduction.
The readings you posted are good; do you know your P04 reading? There could be a inbalance in the two (N03 & P04).
With a KH of 3 and PH of 6.8 gives you 14ppm of C02.
With a KH of 3 and PH of 7.0 gives you 9ppm of C02.
14ppm is good but 9ppm is to low, to help get rid of algae you need to get the C02 between 20-30ppm.
If you have normal florescents then it is 10watts per foot. It should also say on the bulb.
I would either buy a P04 test kit or have your LFS test it for you. If you have an inbalance in your N03 & P04 or high P04 both can cause a algae. If keeping plants a P04 test is one of those much needed test kits.