Help! understanding 'spectral irradiance' and choosing a 1000w bulb/ballast combo

[rjlonergan]

Hi all,

Newbie here.

I am interested in purchasing 2x 1000w 20k (or 14k) bulbs. I have been comparing spectral plot data of various bulbs, and am now confused about what I am seeing.

If I am understanding correctly, are the graphs showing the amount of watts it takes to generate that particular wavelength across one square meter? If so, I imagine that the lower the number, the more efficient the bulb (more light output using less watts, perhaps less heat?)

Or do I have this backwards? The higher the figure, the better? See attachment for example, CoralVue @ ~1.4 watts/m^2/nm. Is this a GOOD result , or bad?

Any clarification on this would be appreciated. Also, most importantly, what bulb and ballast combo would you guys recommend? I am trying to boost ~450 nm as much as possible, as efficiently as possible (using 1000w e39/40 mogul bulbs, any compatible ballast).

Thank you for your comments.!

 

[onetrickpony]

why would you need 2 1000w mh, what are you trying to accomplish

 

[sirreal63]

Your plot is 3 different 400 watt bulbs, the different "K" rating of the bulbs is the difference in the results but all of the bulbs are running off the same 400 watt balance. Out of curiosity, why 1000 watt bulbs?

 

[rjlonergan]

I know that the attached plot is of 400w bulbs; I can't find any for 1000w. I'm just trying to figure out how to read the darn thing. I'm trying to accomplish lots and lots of light in the ~450 nm range with minimal hoods, ballasts, bulbs... Can't seem to find solid answers anywhere.

Anyone?

 

[jedimasterben]

w/m2/nm is a measure of total light output across an area, not input required to make a certain output. In the case of the graph, it is there to just show the spectral difference between the three bulbs and is normalized to 100 micromols of PAR on each reading.

 

[rjlonergan]

THANK YOU JEDI!

So then, in reference to the graph, the 20k bulb would have a higher light output (particularly @ ~450 nm) across a square meter than the other two color temperatures tested?

Last question, I promise

 

[jedimasterben]

According that particular graph, in theory, yes, but in practice, lower-kelvin bulbs have higher PAR. This is due to it being easier to covert energy into red light. A red photon has less than half of the energy of a ~450nm photon. As far as photosynthesis goes, a photon is a photon despite the difference in energy. Corals are more efficient at absorbing 420-500nm light, with ~470nm being the peak for most corals due to PCP shifting the chlorophyll a peak absorption there, but they can realistically absorb across the entire light spectrum.

 

[rjlonergan]

Excellent, excellent, information. You have answered my questions.. Given your expertise, if you have a recommendation on a bulb and ballast combo that you feel would work for my needs, it would be greatly appreciated. Brands, digital vs. electronic, Pulse vs. probe.

Thank you x 1,000,000.

 

[jedimasterben]

Oh boy, that's asking to start a flame war LOL


Let's start with the basics - what size tank/area are you lighting, what look do you like (such as color temp, how blue do you want it?), and what kind of corals are you lighting?

 

[rjlonergan]

Leaning towards 20k. The photos I have seen of Radium 20k bulbs induce mouth watering, although I can't find one in 1000w. I suppose just a bulb with a high CRI (one that is actually the color temp it claims to be), and one with maximum PAR / spectral irradiance (with respect to said high color temp). ..and whichever ballast is best suited for the bulb of choice. So far I've found 1000w 20k CoralVue SE bulbs, but have not heard much on these, and have no idea which ballast is best suited for that bulb (for max performance and efficiency). ~6' x 3' x 3'. ..and I'm not concerned with high energy bills or replacing bulbs more frequently. Thank you!

 

[jjk_reef00]

I'm not sure how set you are on the 1000w bulbs but there are plenty of tanks using less power with great success. I'd spend some time on the large tank forum and see what your options are:

http://www.reefcentral.com/forums/showthread.php?t=2073747

http://www.reefcentral.com/forums/showthread.php?t=2096730

 

[jedimasterben]

There is a 1000w Radium made, but it would probably need to be special ordered from any of the typical places. They are distributed by Coralvue, so you could email them and they could get you to the right people.

36" tall you could still light with a 400w bulb, I would probably supplement it with LEDs or T5HO though to fill in the gaps and give full coverage to the tank. You would need a very wide reflector to cover the 36"x36" footprint.

1000w bulbs would need to be hung several feet above the tank to avoid burning corals. I honestly don't eve know what kind of ballast it would need to be run on, but I'd imagine Coralvue could give more insight to that. Bulbs of that wattage are just not common enough for people to know a lot about them lol.

But again I would choose the 400w Radium instead. Maybe pair two of those with either two Coral Plus and two Blue Plus from ATI (60" bulbs) or LED strip lights from some place like BuildMyLED to give better coverage and more penetration. The 400w Radium is actually a 360w bulb and are only spec'd to run on a European low-current pulse-start M135/M155 ballast or you will overdrive the bulb, significantly changing the spectral output (and it looks like garbage IMHO) and reducing its lifespan considerably. Not being worried about bulb change costs is one thing, but purposely running the bulb incorrectly and spending the extra money on it is another

To quote a user from a past thread about the Radium:

The Radium 20,000K 400-watt lamp is designed for a European reactor low lamp current (approximately 3.2 amps) ballast. Radium only recommends a pulse start magnetic ANSI M135/M155 ballast in North America. This ballast provides the same lamp current as the European low current ballast. Other ballasts overdrive the lamp beyond the lamp specification. Even most electronic ballasts push the lamp past the rated wattage. The Radium is actually rated at 360-watts nominal. This wattage is only achieved with a magnetic ballast. The Radium 400-watt lamp requires the same lamp current as a 400-watt rated 3.2amp lamp but operates at a reduced voltage. A magnetic ballast just limits lamp current and the lamp sets the operating voltage once the lamp reaches an equilibrium.

Using other than the recommended ballasts for lamps usually results in reduced useable lamp life, color shift and a light output difference.

See this for more information on bulbs, ballasts, etc: http://reefkeeping.com/issues/2007-03/sj/index.php

 

[rjlonergan]

hmm

hmm

Now I find myself wondering if the 1000w 20k Radium will have the same issue (being overdriven by traditional ballasts)? I have contacted them, in hopes of figuring out exactly what ballast to purchase if I go that route.

As opposed to large reflectors, I was considering using air-cooled tubes with NO reflectors, running Orca Film along the 'ceiling' above the glass instead. Thoughts?

 

[jedimasterben]

I'm pretty sure that a 400w bulb with a badass reflector will outpace the 1000w bulb with no reflector. You'll still have the immense heat to deal with, as well.

 

[onetrickpony]

a good designed reflector that focuses light where you want it is the way to go, a 250 or 400 will out perform a 1000w with out a reflector. design over brute force

 

[rjlonergan]

HID reflector vs. orca film

HID reflector vs. orca film

This was my idea for 'reflectors' (see attached photo). Essentially it's a perfect half circle w/ a diameter of 3 feet, centered above the glass. The graph that I posted above, claims that orca is the most reflective material across the whole spectrum. Have no idea if it is a valid claim, but in theory, wouldn't it be more effective than anything else?

Thank you for all of your replies. I've learned a great deal thus far

 

[onetrickpony]

Jedi could point you in the right direction with a Bridgelux and Luxeon M that would easily put a 1000w to shame with optics

 

[onetrickpony]

google lumenarc and Lumenbright reflectors

 

[sirreal63]

The shape you are considering would be better than a flat one, but there is a lot more to it. A properly designed reflector suits the purpose intended. Some are designed like spotlights, sending the majority of the light in a tight bean downward so that the bulk of the light is concentrated in the center. Others are more of a floodlight, which will spread the light more evenly over a larger area. Considering the dimensions I would be looking at reflectors that will adequately cover a 36x36 area and a bulb/ballast combination that will have enough punch to penetrate the 36" height.

This will help a little in understanding shape and design. Two reflectors may have a similar shape but function opposite of each other.
http://www.advancedaquarist.com/2009/1/review

I am using a LumenMax large with a single 250 watt Radium and M80 ballast to cover a 40x40x17" area. It is effective enough that I have the bulb about 14-16" above the water and have more than enough light to keep SPS happy on the sand.

 

[rjlonergan]

hell yeah

hell yeah

Wow, those are some badass reflectors. Thanks for the link. So in other words, I should buy Lumenbright 24" reflectors?


"The Lumenbrite ... more suitable for tanks 3ft or less in width. They tend to provide a more focused coverage and higher peak values than the Lumenmax and Lumenarc reflectors. This can allow for better use in taller tanks, as more light can reach the bottom, or allow for higher placement of the lights thus reducing the heat dissipating in the water, or allow for higher light values to be obtained lower in the tank. This would allow the user to create a reef with a much lower rock profile."

THANKS FOR YOUR HELP EVERYONE! :bounce1: