# low bay or high bay?



## jazzlvr123

i was going to buy some 400 watt warehouse ceiling metal halides for cheap on ebay and i was just curious on what the difference was between low bay and high bay metal halide setups and which one is preferred when used for aquarium lighting?


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## goalcreas

FYI, this is what I found on a quick search. don't know if it answers your questions, but it will tell you the difference and it is basically in the height of the building that a light fixture is mounted - low ceilings or high ceilings.

Ceiling heights 
In the lighting industry, we often hear talk of "high bay" (also called hi-bay) and "low bay" (lo-bay) lighting. What does this mean?

In the construction of some types of industrial facilities, a skeletal framework is used, which forms an interior subspace called a "bay," which in turn marks the space as "high bay" or "low bay."

An older definition designated high-bay to mean >25 ft. off the floor, medium-bay to mean 15-25 ft., and low-bay to mean <15 ft.

Some manufacturers define high-bay as being over 15 ft. or 20 ft. off the floor.

The Illuminating Engineering Society of North America (IESNA), the authority in lighting, categorizes spaces as either high-bay (>25 ft.) or low bay ( <25 ft.).

The terms "hi-bay" and "lo-bay" also refer to fixtures designed for these applications, although it is not uncommon to see hi-bay fixtures in low-bay applications, and vice versa.

Metal halide: standard choice for many high/low bay applications 
Metal halide is the dominant light source in many high-ceiling applications in warehouses, industrial buildings, gymnasiums, all-purpose rooms and big-box retail stores. At higher ceiling heights, 250W and 400W sizes are common. High pressure sodium lamps are also popular; for this article, however, we will focus on metal halide.

In review, the core operating components of a typical metal halide lamp include three electrodes within an arc tube that contains mercury and other metals in iodide form. One electrode is used for starting, and two for operating. The arc tube is constructed to withstand the internal high temperature and stresses of HID lamp operation. The tube is enclosed in a borosilicate glass bulb that is also highly heat resistant. These lamps are called probe-start metal halide lamps, or simply metal halide lamps.

These lamps are compact, rugged, powerful point sources. They produce enough light to cover a large space with few fixtures. A 400W standard metal halide lamp, for example, produces 36,000 initial lumens. Some standard metal halide lamps are rated as high as 41,000 lumens. They're also efficient and provide good service life. At 10 hours/start, the service life of a 400W metal halide lamp is rated at 20,000 hours.

Compared to fluorescent, metal halide lamps have several distinct advantages. Metal halide is a powerful light source offering high lumen packages, and, depending on the application, can present a lower installed cost due to fewer fixtures. They are able to operate reliably in a wide range of ambient temperatures, including very cold environments, where fluorescent performance can be dramatically impaired (except for induction lighting, which is considered part of the fluorescent family). And numerous models are available that are specially designed for a wide range of demanding environments such as hazardous locations.

Despite their advantages, standard metal halide systems do not include any dimming capability, experience color shift over time, require four minutes to start, and require about 10 minutes for re-strike after shut-off. Most significantly, at 40% of service life, light output and efficacy experience severe degradation. A 400W metal halide lamp, for example, may produce 36,000 lumens but 25,000 at 40% of life, a 30% decline. Therefore, unless the lamps are periodically group-relamped, a large system's "average" performance over time is much lower than its initial ratings.


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## JG06

High bays tend to run a bit bigger in terms of the overall fixture because they're designed to hang way up high. And the rule of thumb I used when I was the company lighting guy was you'd want a high bay if you were hanging the fixture 18 feet or higher. A 400W high bay is pretty big fixture once you factor in the lens. It also gets real hot and is very bright.

Today if I were looking to illuminate a shop or garage I would look at a high output T5 "F-Bay" fixture which is basically a big 4-6 lamp T5 fixture with _lots_ of reflective material behind the lamps. You get the same basic visible light output as a bay luminaire, just without all the heat and higher wattage consumption of the metal halides. In fact, a co-worker of mine calculated the wattage cost difference (based on 15.4 cents/kWh) would pay the difference in the fixtures in short order.

Now with all that said, whatcha need something this big for and how are you planning to rig it up?


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## jazzlvr123

thanks your guys info helped a lot, i purchased a huge 400w high bay warehouse light for a 200 gallon tank and now I am thinking it might be overkill My plan was to build a hood with this light and install two ventilation fans one on each side of the hood, but my only problem is i only have about 10 ft hanging distance above my aquarium, so due to that fact that i have limited distance from the ceiling to my aquarium do you think I should invest in some low bays or will the light I purchased be ok with a cooling system build in? I attached a picture of the light I purchased if it helps thanks


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## goalcreas

Do you have any sketches of what you had in mind doing with these.
It would help me give you suggestions If I could visualize what you are trying to accomplish.


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## Muirner

I really dont think that the light will be suitable for being in a hood. I think it's going to get way way to hot and pose a fire risk, also the hood would have to be 10' tall so that it could hang as high up as possible. In an open hanging situation you may be able to get it to work, but can i ask, Are the bulbs suitable for aquariums?


EDIT: Just read ponyrandy's post and relized i forgot to mention something. The amount of heat that would be vented into the house would be enormous. Almost guaranteeing the need for an A/C unit in the room all year round. It's going to be a monster, and with that comes heat. Make sure that everything around it can withstand the heat, somethings may melt others may reach a flash point. Be safe!


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## ponyrandy

From my experience with metal halide lighting a 400 watt light is a 400 watt light. What makes them a high bay or a low bay are the reflectors and lenses. If you look at high bays, they have a deep reflector which directs the light downward from a high ceiling. The low bay lights usually have a shallower reflector and a lense to diffuse the light outward from a lower ceiling. Trading these in on a low bay light to me would be pointless. By hanging theones you have lower, you are directing the light into a smaller area which is what you would want, a more focused light to go over the tank. The downside is the heat these monsters produce, and the closer to the tank the worse the heat problem. If you run cooling fans, I assume the tank is indoors, unless you run a vent outside, you will just vent all of this heat into the house. 
Brian


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## jazzlvr123

Ok so my aquarium is right next to a window so I just wrote up some plans of how I am going to build my DIY metal halide system using a 400w warehouse light 120v ballast using two electronic fans, one sucking air into the hood and one expelling hot air into a 2 foot long tube which blows it out my window any constructive criticism would be appreciated before I start this project next weekend thanks


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## jazzlvr123

i noticed it came out real small if you give me your e-mail i can send you the plans, thanks


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## Muirner

How big are the fans that your planning to use? If i were building that system, i'd also leave as much open space as you can. ie/ the top, if you can leave most of that open you should be doing pretty good. Also check out my link in my sig. You'll see i leave the back of my hood open for heat exchange. I have about 6-8" of open area so i can let hot air out and cool in. That's only for 4 x 32 watt T8's


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## jazzlvr123

Well I wanted to build the hood closed so I can expel all the hot air though the tube and outside through my window to avoid releasing any hot air into my house this would also make my room cooler allowing cooler air to be sucked into the first high powered electric fan any problems you might see in this idea?


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## ponyrandy

Couldn't tell from the drawing but aren't you drawing conditioned air out of the house and blowing it outside?
Brian


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## jazzlvr123

yes, it is blowing cool hair through the hood cooling the halide and expelling hot unconditioned air outside, but we hardly use the air conditioner, and i think i might just use cool burning fluorescents on real hot days so the tank wont cook.


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## ponyrandy

My only thought would be to run the intake air outside also, drafting the outside air in over the bulbs and then exhausting it back out. You must be in a cooler part of the world than I am. I am in Houston, Texas and we run the a/c most of the year and sending conditioned air outside is a big no no. You could also incorporate a thermostat on the fans that way they only run when the temperature inside the hood gets to a certain point. 
Brian


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## JG06

Study up on how metal halide pendants work and maybe you can glean some information from that. I'm thinking that a pendant is what you had in mind when you bought the warehouse light and since you have the ballast and lamp base, you might be able to put one together.


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## jazzlvr123

hello just wanted to tall yall i finished the hetal halide hood and you can see it and read about it on my new thread: 
http://www.aquaticplantcentral.com/forumapc/aquascaping/40721-my-new-diy-180-gallon-naquarium.html

thanks for all your help guys it made a big difference


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## jazzlvr123

hello, i have installed a 400w metal halide into a custom hood for a 180 gallon tank about a month ago, i noticed that even this was not enough light for my large tank so i just purchased a 400w high pressure sodium ballast kit on ebay right before i posted this thread giving my tank a total of 800w once the hps arrives and is installed. my question is, i noticed that most high end light fixtures focus around metal halides and high output T5's but there are not many (or any) aquarium hoods that include HPS, is this because aquatic plants react differently to hps than non aquatic? I have read that Metal halide is for the vegetative state and that high pressure sodium is for the flowering state but do aquatic plants have a flowering state? will my plants (mostly my hc and riccia) benefit from the addition of a 400w high pressure sodium light? or am i better off just adding more T5's to increase the light intensity? any advice would be greatly appreciated and thank you, kyle


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## ponyrandy

If I remember right, high pressure sodium lights are the ones that have an orange glow. They put out more lumens, but a metal halide has a whiter light. Even if your plants liked them, I am sure you will not like the orange glow in the aquarium.
Brian


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## jazzlvr123

so do you think i should buy the MH conversion bulb for HPS ballasts insteal of using an HPS bulb?


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## ponyrandy

Don't know the answer to that one. I have never heard of a conversion bulb. I would look at dollars spent on converting versus buying a suitable MH though. 
Brian


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## jazzlvr123

http://cgi.ebay.com/ws/eBayISAPI.dl...MEWA:IT&viewitem=&item=270129290878&rd=1&rd=1
theres the bulb i would use, thank you kyle


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