250W MH distance from waterline

[wom001]

Good Evening all,

Im starting my 72 days of going fallow (Progress not punishment) and this is one of my first projects to complete. Im finalizing my hood design and wanted some feedback on optimal lighting distance from the waterline I should be shooting for. I plan for it to be fully adjustable but i wanted to atleast start with a baseline average so I can adjust it as needed. Here are a few details of the tank.

260gallon = 72x30x28D
Lighting - Lumen Brite Se reflectors, the original size not the minis. Im planning on using 250w on this set up but I am planning on getting switchable ballasts to bump that up to 400 if needed. Plan is to be fully SPS dominant but to also include a zoa or acan garden with some montis and clams sprinkled in.

Anyway would love to hear some thoughts!

 

[OPtasia]

Go ahead and bump it to 400 watts if you're going SPS. Make sure you protect that bulb in a housing of some sort with active fan ventilation. Those bulbs run hot and if a stray droplet of water hits the bulb, it'll shatter. Also, be very careful not to get any fingerprints or skin oils on MH bulbs as that can cause them to shatter, too.

On my last big tank, I ran 500 watts (two 250's + 48" actinics) on a 180 gallon tank in a PC fan ventilated hood with plexiglass shield over the bulbs. It sat about 3 feet over the water line of the tank inside of an enclosed canopy.

You could always check with a local aquarium group to see if anyone has a PAR meter you can borrow. You'll want it close enough to give you decent PAR but high enough to avoid heating up and evaporating the water too bad.

 

[jda]

I like the bulbs to be about 10-12" off the water with m80 or 400w. This allows the fans to blow across the surface and render the heat nearly meaning less, and I can get my shoulder and arm in there to mount frags and work in the tank. For more punch deeper into the tank, I have gone as low as 4-5 inches.

I would say that a system that can move between 6 and 15 inches is probably good.

The only ones that I had to mount higher is the LumenArc Mini which is made to penetrate deep and not spread all that well... this one had about 1000 PAR 6-8 inches under the water with the bulb 12" from the surface and I had to raise it up to get that down to 700-750.

Get a good PAR meter at least on loan. It can really help you decide on stuff. The newer apogees (5o0 series) are easy to use. Let us know what kind you got and we can help with any kind of correction or adjustment factors that are needed.

 

[Dana Riddle]

Consider the maximum distance the luminaire can be off the waterline. I'm not familiar with your hood/housing, but can say that metal halide lamps, acting as point sources of light, almost always create hot spots. I agree with previous comments - a PAR meter is an important tool. When taking measurements, do so with no pumps on - any surface agitation creates shimmer that cases readings to jump up and down wildly and can be frustrating.

 

[oreo54]

These should help...Believe they used a 400W bulb.. This is more for spread determination than anything else.
12" tiles...
You just need to determine "where" you want the most, or any light...That will determine your height..
http://www.reefcentral.com/forums/showthread.php?t=1664775

All four reflectors did light up the 36" x 36" grid nicely, more than the pictures indicate. The camera picked up on the hot spot each time

Just a note though.. Cameras don't lie..
bit more practical information:
http://reefcentral.com/forums/showthread.php?t=1531096&page=26

 

[jda]

Those look about right... I am 1300-1500 at the top of the water about a foot under the Halide (250w on m80). You can get a lot more PAR than this with smaller reflectors.