ok, so one problem here.. if you only go with 3 bulbs then you will have to lift them up to around 16" or more to get an even spread across 8 foot.

since you are lifting them the PAR values are going to drop in the tank and you are also thinking of dropping down to 250's . 250 watt is not always a down grade from 400's but with the ballasts you are looking at ya they are. so now you are lowering your PAR even more.

I recomend that you stay with 400's if you want 3, or go to 4 MH if your dropping to 250's on an electronic ballast.

I would personaly go with 4 bulbs either way, but I also like lots of PAR.

Steve

I agree. 3 bulbs/400W 4 bulbs/400W or 250W

My 750 is 8feet long and 5 feet wide, I am only using 2x175w single end in Lumenmax Elite reflectors with 2 6 foot VHO flourescents for supplementation (all about 16" above the surface), I have not checked par but there is no shaded spots and the tank looks pretty well evenly lit, granted it is a FOWLR but there is one anenome in there that is doing well, If I ever switched it to a reef I think I would add a third reflector and bump it to 400w, it all depends on bulb choice and reflector type IMO, I am running 3 400w SE on the 300 reef and the 750 still looks brighter visually, again I do not have a par meter to compare the important numbers.

i have 2 400's over the 5 footer and its 16" and i have overlapping all corals seems happy to me i guess.

Meh, if it's all LPS and lower light clams I don't think you need 400w (even with just 3 bulbs), although it wouldn't be a bad idea with your bulb choice.

You would get much more PAR if you use a Phoenix bulb (although SE are tough to find), and with some UVL Super Actinic VHO you will still get quite a blue look. I actually even find the UVL 454 to be brighter and even more fluoresce intense than the Super Actinic.

ya i heard that Mindy about the phoenix i loved them when they were on my DE 250's to bad i wont go back to DE only because of the bulbs how they are made. i hate when i break a 120 dollar bulb,

see when i had all my SPS i moved to 400W because sphelps was looking to trade them off so me like to be curious and all, well you know the rest of the story.
I think having the 400's i can push them up higher and still achieve the par I'm thinking. maybe put a 250 in the middle

Where are you paying $120 for a 250w Phoenix DE? Eep! Should be $65-85. I have never broke one, what the heck were you doing with it? I have someone trying to get 250w Phoenix SE for me...hopefully that works, and I can share my source! :D

It was a megachrome bulb that I bought and well I pushed on the bulb ends and well she snapped ya I love that bulb just need a 250 ballast now itslikepullinf teen getting one some people are freaking lazy to ship a small ice cap ballast local shipping meh kiss my &&@

I hear ya.