150W vs. 250W

[amundine]

Hello,
I have a question about which light to go with. I have a 75G glass tank (20" deep). 2-3 inch sand bed. I am planning on a mix of LPS and SPS corals and want to keep zoas too. I am finding a very small price difference between 150W retro kits (HQI) vs 250W retro kits (HQI). I'd always thought that 150W would be enough for me, but I've also heard countless others advocate the highest wattage you could afford.
Can anyone provide me with any insight as to which wattage would be appropriate for the animals I plan on keeping.
I am also curious about Kelvin values. I know that the higher K value, the bluer the light coming out. What range or portion of the spectrum is best for most SPS corals? Is the same range or portion of the spectrum best or even good for most LPS? Will it be too much for zoas on the bottom of the tank?
Please let me know. Thanks,
Drew

 

[Urban_Squrill]

I would suggest go for the 250s. I was trying to decide witch to go with with my aga 75. I finaly went with 250's because I could keep anything I want and the softies really like the 10k 250's.

 

[BeanAnimal]

There are plenty of 150W bulbs that are brigher (more PAR) then some 250W bulbs.

150W is certainly enough light if you choose the right bulb. That will also depend on the color you want and if you want to add supplimental T5s or VHOs.

10K 250s are more light than most people would want or need.

Overkill? That is up for opinions. Do you really want that fast of growth in such a small tank? Too fast and it becomes hard to manage.

Can you give us an idea of what you have seen (color wise) that you like?

 

[DarG]

My take on it is that going with 250 watt allows you more choices in bulbs from a color standpoint. There are some 150 watt bulbs that will give you plenty of light but if you wanted to go with a bluer bulb, the par usually drops out so 150 watt limits you in that regard. Reflector choice has a large impact as well. Of course, you could add T5 to the equation so that it is not just supplemental but actually provides the primary light source or is as predominant as the halide itself.
Going with 250 watt though gives you more flexibility in bulb choice. I have a 90 gallon but only 18 - 19" deep. I just switched from 150 watt to 250 watt mainly for the reason stated above.

 

[amundine]

The 75G I bought came with 2 VHO lights in the hood, so I was planning on leaving those in place for supplemental lighting. I was also looking at a retro kit wit dual 150W or dual 250W MHs combined with 2 54W T5s (http://www.hellolights.com/index.asp?PageAction=VIEWPROD&ProdID=1357)
I can just jam all of that into the hood. I'm thinking it'd be overkill though. I don't just want my animals to survive though I want them to thrive so I'm trying to get all of my planning right before I introduce them.
I feel a little too ignorant right now on what "the right bulb" would be in terms of wattage, Kelvin value, and brand name to just throw my hard earned money at something without more info; hence this post I really appreciate the replies, thanks.
Drew