I don't really know how running a sol with the light you have on your tank will work to be honest. I think you might end up with two very different looking sides if you run it the way I image you would, especially the sol blue having a much different ratio of white to blue.

Three Pro's can run on one of the power supplies, in addition you can use any 24V power supply so you could easily power four of them with a single power supply that will run for $20 or less. I figured the more module design of these would be a better addition and more easily blended with the existing light.

You could also probably rig up some kind of DIY kit to work similar to the Pros, my guess that a decent 24 x 3W LED kit would run you around $250 unless you wanted something controllable.

yup, thats what I thought, so why not buy a second one and run two over the tank?

Steve