2 x 250 Watt MH bulbs too much for a 75 galon tank?

[spider crab]

Hi,
I guy I've been working with at my lfs told me he thought that 2 250 MH lamps would be too much light for my 75 gallon tank.
My intent is to keep a wide variety of corals/sea life in this tank including: sponges, mushrooms, leathers, gorgonians as well as sps and possibly clams at some point. I had also intended to augment with one or two 110 VHO's.
Is this good advice? My thinking with going with 2 250's vs 2 175's was that:
1. There isnt much difference in price between the two
2. I might eventualy do with a larger tank in the future.
Will I be limiting myself by choosing the 250s in terms of some some of the less light tolerant corals? Also the 250 burn more electricity and possibly produce more heat.
I'm planning on hanging the lighting in an open backed canopy roughly 8 inches above the waterline.
I also need advice on the color temps for the MH and VHO lamps given the above range of coral I'd like to keep.

 

[richard rendos]

Not too much light. I would even consider going to 400 watters if you plan on a lot of SPS/clams, but 250 watters + VHO is probably good too.

 

[slothy]

well if you shop around, you will see there isnt much price diff from 250 to 400 mh

 

[conundrum]

The question is are you willing to shell out for a chiller and controller? You may need one with the 175's, probably with 250's and will with the 400's. Cha-ching. The cost is not that different, the electric bill is another matter...
If you think doubling your efforts can compensate for lack of skill, there is no end to what you can't do.

 

[broomer5]

Over my 75 glass tank - I'm currently running
Two 250 watt Ushio 10,000K MH powered by PFO Dual 250 watt HQI ballast
AND
Four 110 watt URI VHO bulbs powered by PFO Dual circuit ballast.
MH are 12 inches from water surface
(2) VHO are 12 inches from water surface
(2) VHO are 15 inches from water surface
My water temperature is steady between 80-82 F
Room temperature now is at 70 F
No chiller
Canopy ventilation, fan placement and ambient room temperature are all key to keeping heat down IMO

 

[broomer5]

I should clarify myself here ...
I do have 940 watts over the tank - but I do not run them all at the same time - for the full lighting duration.
I'm sure this has a lot to do with keeping the tankwater cool
I run one MH for 6 hours
I run the other MH for 6 hours
With a 3 hour overlap
The VHO
220 watts actinics on all day from 12:00 noon to 9:00 pm
220 watts 50/50 on random timer
Thought I should make this clear regarding heat issues.

 

[conundrum]

spider crab is in N. CAROLINA, ever been there in the summer. The temp won't be 70, it's hot and humid. Let's do the guy right and let him know what he is probably in for if he decides on 2 400w MH and 2 VHO at real temps on a normal 6/13 hour use in his location.
I watched my friend go thru this on the exact same setup, he kept room temp at 74 in summer, that is low for phoenix, most keep it at 78, and could not get by without a chiller, he ended up trying 4 hood fans and a sump fan before purchasing a chiller. The tank temp would spike 6-8 deg by 3pm. It would raise the room temp to 80.
Broomer5, your temp is already at the upper limit, could you please let us know what do you do in the summer?
please understand spider crab, I am trying to let you know what usually happens when you get 2 big honkin MH lights, clip them on for the first time and watch your tank try to turn into a hot tub. I would be realistic and go for the 250w, you should be able to make that work, even in the summer.
"Hope for the best. Plan for the worst."

 

[broomer5]

I run the AC and as I mentioned - I stagger the time the lamps are on.

 

[spider crab]

Conundrum,
You have a good point when you mention the heat in NC during the summer.
As it turns out, I ordered 2 250's on monday so It sounds like I'll be ok. To be honest, I was concerned about the electric bills as much as the heat. With 500 Watts of MH and 220 Watts of VHO that gets me to nearly 10 Watts per gallon on a75 G tank, which ought to be plenty. I'm hoping my bills wont go up too much.
The canopy I am building will be open backed and I am going to see what it does without fans first and add them later if it gets too hot.
Anyways, I appreciate everyone sharing their experiences and I'll let you know how it turns out.