How Many AI Mods for a 90 Gallon Tall

My 90 gallon mixed reef is 48 L x 18 W x 24 D. Currently I am running the Outer Orbit fixture with 4 Geisemen T5's and 2 250W Pheonix 14K MH bulbs.

I have one green carpet nem at the bottom of the tank, around 24" from the MH and a RBTA about 16" below the other MH. Both are florishing very well under these lights. I also have several (30+) SPS corals growing under these lights. The lowest SPS is around 18" below the MH. I also have 10+ LPS growing at all levels of the tank under these lights.

I am debating on the AI SOL blue LED, but if I have to have 4 modules ($2300) I cannot really justify the savings at this point. Does anyone know if two modules would be enough for my mixed reef or will I have to have 4 modules?

 

2 should be plenty! The 12" rating that AI gives seems overkill for most systems.

 

i have 2 AI's coming in next week and i have the same dimensions as yours. a friend of mine brought in his 2 Ai and we tested them yesterday and was not satisfied with the spread. we placed them 12 AWL, parallel and still have dark spots mostly by the center brace.
2 AI will work depends on how you set it up. my plans for mine will be placing them parallel and 12m AWL and re-doing my rockwork. i will have to reduce my live rocks by the middle and focus more under the AI's.
hopefully i won't have to order more modules.

 

This is two Sol Blues mounted parallel and 12" above the water. No dark spots.



Notice how the light strikes the canopy back and sides about 9" below the fixtures showing coverage is side to side and front to back.