Blue-green slimy stuff

My 10-gallon plant tank is starting to grow large patches of blue-green
slimy algae (cyanobacteria?) directly under the one light and on the side
that gets a bit of sunlight each day.

I understand this stuff may be dangerous to fish. There's no easy way to
scoop it out as it's somewhat like an oil slick. And I don't remember what
the general advice is. Can anyone help?

(The tank is kept at 75F with pH at 7.0. Has DIY CO2 and an air-driven
sponge filter. One lamp is a PowerGlo. The tank is packed with plants.
Cardamine lyrata and watersprite have taken over the surface so there is no
surface water movement. Other plants are Java ferns, banana plants, apon.
stachyosporus, sword plants, and giant vals. There are six baby dwarf
gouramis and a 3" SAE. I dose with Flourish and Kent fertilizers
alternately, every week with 20% water changes.)

Greg. Tong
San Francisco, CA, USA
gtong at sirius_com

"Every infinity is composed of only two halves."