My fixture has 20- 3w lights, a combo of half blue and half white. They run full power all the time, unless I want a more blue look at times. I have acro,s less than a foot from them, near the top of my 20g tank

Two units on a 48" tank. No one unit would have never been enough to cover the 48 inches, even with increased intensity. It created uneven lighting, middle 24"-30" was fine but the ends were too shaded.

Makes sense.

Have you considered a vertex or sunbrite?

Not really. I don't want a large fixture, and we all know tanks get upgraded all the time, so I want to be able to expand on lighting if needed. I also insist that all my devices are controllable via my Apex.

ok so why don't you start with two units for your tank. lift them up and see how much area they cover and if you are happy with the intensity and then see how many you realy need.

I think if you want the light out put the same as your 400's you will not be able to lift them to high but unless you have a PAR meter to test them with you'll never know.. and asking on here is just padding your posts :mrgreen:

get on with it and buy a couple already

Steve

Marko had a thread awhile back showing his 3 Sol's over his 180g and it looked good. I have a 36"x24" tank and have 2 Sol's over it as a single unit of either the Sol's or Radions wouldn't cover the area to my liking. I wanted lots of intensity over the entire square footage of the tank with no dim areas on the edges. My height is 12" above the water line and going through a glass top and run at 60%W, 70%RB & 70%B. It took me about 3 months to build up to this level (I used the amount of algae it produced on the glass to know when to increase the level) and haven't seen any need to go any higher. Corals all seem happy and the tank is very bright and pleasing to my eyes.

Ya, I used that as a guide, although he doesn't really have much for coral at this time to see how SPS react.
Dez also uses 3 and has great results, although he did add supplemental strips to fill in the shadows.

don't think 2 will be enough, I'm ok buying three (closer to June). I'll run them and see what happens. If my tank dies, I'll blame you :)

I think 4 units would eliminate shadows but would personally try 3 and then see if the extra cost is needed or not. My tank is only 20" deep so I can't say if raising the lights a couple inches higher and cranking up the intensity to 100% (over time) would give you the effect you are looking for or not. While I'm sure it'll grow coral just fine, beauty is in the eye of the beholder.