Coverage for a HQI 250w

[Reefland]

What is the maximum coverage you would say 1 250w HQI would do?

I am planning an SPS tank and trying to determine the best size for the tank using this as my main source of light. Is 24x24 to great of a spread for this light? Would a 20x20 spread be more reasonable for this light?

Thanks,
Scott Z.

[Ninong]

Scott,

Obviously a lot depends on the quality of the fixture/reflector and the height it is suspended above the tank. The perfect person to ask is Schrocat. I talked him into getting a Giesemann Nova II 250w 10,000K HQI DE for his new tank.

If you are interested in the official manufacturer's opinions, I can tell you that their usual claim (both AB and Giesemann) is a coverage area of 60 x 70 cm (23.62" x 27.56") for each DE lamp mounted parallel and positioned 30 cm above the water. And Giesemann's recommendation for the maximum size aquarium for a single Nova II fixture is 60 x 80 cm (23.62" x 31.50"). http://www.giesemann.de/GB_NovaT.html

[PerryinCA]

24" x 24" would be fine. Just try to keep the needy suckers in the middle 20" if your concerned about it.


I think that geissemann exaggerated thier effective spread by just a little, 31" seems extreme. I wonder what they were using as a standard in terms or minimum necessary lumen/par to achieve this measurement?


-Perry

[Ninong]

Perry,

Giesemann doesn't claim 31.5" as their "effective spread." They claim 60 x 70 cm (23.62" x 27.56") as their effective spread. They claim 60 x 80 cm as the maximum tank size. They are assuming that the outer 2" on either side will not be as well lit as the rest of the tank.

I wonder why they don't simply claim 60 x 60 cm??? Any ideas?

FWIW in the AB fixtures and in the Giesemann fixtures the HQI lamps are all 60 cm apart, center to center.

[Reefland]

Good news! I plan to put some type of "wrapping" if you will around the bottom of the fixture in order to prevent the light from escaping so I should be just fine. I wonder how dark it would be on the ends of a 36" long tank? Too dark for a couple of softies?

Thanks,
Scott Z.

[PerryinCA]

Doh! I guess thats what I get for breezing on through it.

The reason is just do to reflectorlamp design...

-Perry

[schrocat]

Scott,

I'm using a Nova II fixture over the 54g bowfront corner.

I like it it a lot. It 's a clean look, in titanium white. I have no canopy, just a "shade" my daughter made. Eventually I will design a canvas hood (shade).

The bulb seems to keep the one clam I have quite happy.
The fixture is 7" from the surface (measured from the UV filter)

I guess it's covering a triangle approx. 19"x19"x38"

The lower light areas on both front corners are hardly noticeable...

I also pump in a little actinic, (33w) from a modified Ebay fixture.

[Reefland]

Thanks for the input Bryan!

Could you elaborate a little bit on the 19x19x38 triangle? Are you saying it is 19x19x38d?

Thanks,
Scott Z.

BTW, I guess you already know but that was a brilliant idea for Ninong's PC!

[Ninong]

The overall dimensions of a 54-gal bowfront corner tank are 38" across the front x 27" on each side x 22"H. So I guess he has a rear corner overflow that takes up space?

[Reefland]

So in theory the fixture may provide enough spread to cover a 36" long tank? Obviously lower light requiring corals would be placed on the ends where it was not as intense.

On the other hand, if he has 4" of sand in the front (no corals along the 38" span) then the coverage may be reduced to 30" or so?

Scott Z.

[Ninong]

Scott,

Yes, you can light a tank 36" x 24" x 24" with a single 250w 10,000K HQI DE lamp. And you keep any SPS or clams you want in there, just exercise common sense in where you position them. (P.S. -- I almost forgot: it goes without saying that you CANNOT position the lighting fixture 4" above the water. That won't work at all. It will need to be at least 9" above the water.)

Or... you could go to astronomical limits and duplicate HiloJack's tank. Remember him? He has exactly the same tank as Schrocat: 54-gal corner tank. Only he has 2200 watts of halides plus a couple of VHO actinics.

[Reefland]

Yeah I remember that tank now that you mention it. Makes me think of one thing, kilowatt per hour!

I appreciate everyone's input; I am just going to take my time and make sure I plan this tank appropriately. I wanted 36" L but was concerned about the lighting for it; not wanting to go with 2 MH and trying to prevent a need for an elaborate VHO system. In fact, I am considering going with just the 250w HQI between 7 and 10" from the surface. I think it will be enough light for SPS and Clams in the direct light and a couple of nice softies on the ends.

Next step, finding a builder of the tank! :eek3:

Thanks again guys,
Scott Z.

[Ninong]

Scott,

Look at it this way: a 250 watt 10,000K HQI DE lamp is sufficient for any SPS or any clam. It really doesn't matter how much water the coral or clam is sitting in. The coral requires a certain amount of light to reach its saturation point. It doesn't matter if it is in a 5-gal tank or a 500-gal tank, it still requires the same amount of light. So if you place it under a 250w 10,000K HQI DE lamp it will receive the same amount of light regardless of the size of the tank. This is what confuses all those nano tank guys. They think that if they put a couple of 36w PCs over their 10-gal tank that they have tons of light because they now have 7.2 watts per gallon. So what!! They still don't have the same light for their corals that a single 250w lamp over a coral in a 500-gal tank provides. It just happens that they can usually get by because their tank is so small that the coral is practically touching the little PC.

Anyway, another way to put it is that you should measure the light reaching the coral in the tank with a lux meter. That reading is the only thing that matters. That reading times your photoperiod is all you have to worry about, period. How much water is around the coral doesn't mean squat.

[Reefland]

I absolutely agree with that however at the same time, if the clam is not sitting under the light (in a shaded area due to insufficient light spread for a given size tank), it doesn't have a chance.

I realize the light is fine for survival and growth of SPS and Clams, I was more concerned with spread to see if it would be enough to sustain growth of some softies not directly under it.

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If this is the spread the corals on the ends aren't going to get enough light.

--/---\--
_/____\_

If this is, it should be enough to sustain nice growth and coloration.

Right?

Scott Z.

Boy those little diagrams are poor representations aren't they!

[schrocat]

Originally posted by Reefland

BTW, I guess you already know but that was a brilliant idea for Ninong's PC!

Team effort bro...but hey...we bad!!!


19" sides, 38" front...which bows out for a total frontage of 43"
I'll just stick with saying 38"...nothing is crammed next to the front of the glass.

Let me know if you need any reflector specs for the Nova...I was attracted by a sizeable price cut offered by vendors who were trying to get the newer models in last year. Basicly they changed the finish.

Ninong...I remember that 2200w tank! Freaking BEAST!