Then the wierd algae started growing. It is dark green/blue
and very slimy, in the middle it was white.

Sounds like BGA (blue-green algae). Weirdly, that's one algae that's often a
problem in low-light tanks.

I had a lot of it in one tank when it was low-light. Mainly when I didn't
change the water frequently enough. Then, when I increased the lighting to
moderate, I got BGA at the top of the tank, where plants kept the water still.
I was growing my own pond scum. :-P It eventually went away on its own. IME,
it's normal to suffer algae outbreaks as the tank gets established.
Eventually, the tanks finds its balance, and the algae goes away.


Leigh

http://www.fortunecity.com/lavender/halloween/881/