I am planning on upgrading to AI's im getting mixed signals
some people say 3 is enough and some say 6
does 6 sound like overkill or should i just get 3
i have three maxspect over my tank now and getting good growth
any input would be appreciated
Your 210 is somjewhat deep so I would not change out the center lenses to 70 degree optics IMO. Dual center braces, wide glass or thin plastic rails? If wide glass like the Oceanic tanks, I would consider bigdog's recommendation of 3 Radions since the need for more then 3 AI units makes for a difficult mounting layout.
I use 4 AI units mounted parallel in a 180g but if I had corals, it would have started with a minimum of 5 units mounted perpendicular to the front glass and additional units added as needed. I do not have any center braces.
I have a 325 that measures 84x30x30 also with two braces and three openings. I put two units over each opening to start. I have since add two more and a light rail that moves the four units in the center back and fourth from front to back. It is cool have the lights move because it changes the look dramatically as the lights move across the aquascape.
Also with the light moving it gives the corals light from more than one direction.
I would say start with three and see if you need to add more. I have a 180 gallon with the same top brace as your 210. I run 4 Sol blues over the tank, but IMO three would have been fine. I run mine with the stock optics as well.
I have 3 SOL Blue's over my 180gal and they work great. I see alot of people discussing the center braces and although that will play a part in the spread of the light based on the number of braces, width and depth is still the main concern. My tank is 72x24x24. Had it been deeper or wider than 24" I would have used more. Assuming you tank is no more than 24" wide then using them in a parallel to the long tank wall configuration is fine as they will cover that 24" width at 12-14" off the water. If you tank is more than 24-26" deep or wider than 24" then I would consider using more lights and in a perpendicular to the long tank wall configuration.