I'd like to add some MH lights to my 180gallon tank but I've never done MH and the terms are a bit murky. The tank is 6'x2'x2' and it has a custom canopy that's pretty high so it shouldn't be a problem to additional lighting to it. I have three 6' VHO bulbs (two white and one actinic) but I'm assuming I would get rid of the two whites if I had MH lights installed right?

How many and what size watt bulbs would I need ( 3 250w's)? I've never done MH and there seem to be a lot of different kinds. Is there a guide of what to use and when to use it?

I'd prefer European manufacturers since we are planning to move to Europe in the next 1-2 years. Which brands should I look for? I saw on this board about a "10k german socket" What is that?

What is a "PFO setup"?

What's the difference between a ballast and a socket?

Sorry for the newbie questions but I'm not a lighting exert but I'd like some decent illumination in my tank for some corals.

Since we planning on moving in the next 2 years, should I wait until we move before I start adding MH lights??

Thanks