250 or 400? Perry? Ninong? please help

[reddhaus]

I am digging into my DIY hood project. I have already purchased my MH reflectors with sockets. I have not bought the bulbs or ballasts yet.

I have found that the height of the bulb from the water will be about 7 inches. I was guessing that they would be higher in my original plan. My original plan had also called for 3 - 400 watt MH bulbs.

Since they are going to be this close to the water would i be better off to get 3 - 250 watt MH bulbs?

My tank is a 125 AGA. I will be running 4 - 72" VHO's along with the MH. Yes, i am cramming alot into a small space. My house stays air conditioned at 75 deg. during the summer and i should have pretty good air flow. I don't know how much of a heat issue i will have.

Thank you in advance.

[Ninong]

If your tank is a standard 125-gal glass tank, 72"x18"x22", then I think the 250 watt size would be more than adequate, especially with 640 watts of VHO supplemental lighting.

[reddhaus]

That's what i am thinking but i just wanted to confirm it with people that have more knowledge and experience than myself. The 400 watters would be alittle overkill i think.

Thank You.

Isn't Reefland great........

[Poseidon]

I agree that 400 watters would be overkill, but the reflectors make a big difference. I have the "spider" type reflectors and Matt has the flat Reflector... AND HOLY COW is there a BIG difference!!! I have 2 250W 10,000 K AB bulbs, Matt has the 10,000K ushios and mine has a much more even distribution over my 135, Matt's light definately have a distinct fall off at the ends of the tanks... I plan to add a 3rd Light eventually, but for now the 2 will have to do...

Next the Ca REactor and a BIG ol skimmer!!!

[PerryinCA]

I am gonna go against the grain and say that much of your needs will be determinded by the type of reflector that you utilize, and type of tank you desire rather than the wattage.

Light falls off dramatically in a relatively short distance when utilizing synthetic sources. While it is possible to have equatorial levels on the surface, it's reasonable to assume that in the same tank you could have 120ft deep measurements at your sand bed. 400w allow more photon flow. If you utilize a reflector to achieve a high level of uniformity, you won't see photo-inhibitive light levels anywhere in the tank, and will have a better over-all coverage.

However, when you factor in practicality, you add a whole other dimension to the equation. For a tank that size, you could really have some issues with temperature, and unreasonably high electrical costs.

There really is no quick answer to your question. In my opinion, 1200w of light over that size tank is not overkill, but can be somewhat impractical to us average Joe's.

In reality, with proper placement and effective luminaires, 250w lamps should suffice just fine.

Regards,

Perrt