Red Slime Algae - Help!

[ABSC]

Hi there, can anyone help?
We bought a second hand Marine tank from a friend approx two weeks ago, it was shipped with all live stock and matured water and the first week it looked absolutely awesome but this second week it has been taken over by red algae. We have fitted a ceiling mounted light setup which has two T5's, one Halide and two moonlights in it and in total these are on for approx 12 hours a day. The previous owners have told us that they never had any red algae problems previously so I'm just wondering whether there is something about these lights that is triggering the rapid growth? Maybe we've got them too close to the tank? (They're approx 12 inches from the top of the tank)
Also can this red algae harm the fish as I've never experienced it before?

 

[dilbert]

Also can this red algae harm the fish as I've never experienced it before?

Some or all of them contain or release cyanotoxins. That is normally a general health issue on shores and harbours where people is swimming or getting food out of the sea.

But my red-legged hermit crab eats it if there is nothing else and I haven't seen fish suffering from this.

Light is normally a minor issue. Surely, without light they wouldn't grow at all, but mostly it's phosphate and in high-flow areas they have diffculties to attach and accumulate therefore in low-flow areas.

I was wondering how did you ship a tank with live rock and matured water? Taking out everything and shipping separately, I guess.
Maybe somehow, a lot of phosphate came into your tank. Do you have figures of phosphate before and after this action?