I have sunpod 2x 250's on a 72 bowfront and it is awsome. It should be ok, but how the tank will look IMO will depend on the K rating 10, 14, 20 on how blue you want it and how fast you want stuff to grow.
i think that it is overkill...you can keep anything you want with 2x250s and wont have to worry about heating issues to much or power bill being super high...i have 2x250s on my 90g 15inches above the water have have no problem with keeping anything
you will be able to keep whatever you want but in my opinion it is way OVERKILL you can get the same results with 2x250s or even better yet 2x 175s...and you will still be able to keep whatever you want...i have 2x250s on my 90g 15inches about the water surface and can keep it all...my low light corals thrive at the bottom of the tank and higher demanding ones in the middle-top...save yourself some money on the powerbill and the cost of the setup/replacement and go with a lower wattage bulb
IMO that is overkill for 55g. You will have to keep the light way off the surface and have big heat issues.
I'll have 2x400W on 150 and I was told that it's almost too much.
ok cool....not of caution...if you already have tank inhabitants fish/coral you will need to light acclimate them before blasting them with the new intensity of the halides by either using door screen or something else that will kind of shade the light for a few days until they get used to the light....and it is always best to try to keep your halides 8-12 inches off the surface of the water