Let's stop and review. In Chapter 1 I addressed fish-only tank lighting requirements, including using pre-manufactured light hoods for these types of tanks, was well as the possibility of using them for keeping "some" reef life.
In Chapter 2 I covered the basic fundamentals of NO/Standard and VHO fluorescent tubes, such as how CRI or Kelvin determines a bulb/lamp's color frequency, how wattage is beneficial and why it's important, and fluorescent tube wattage comparisons . Depth simulation has also played a part in our lighting selection process.
Now that we have a better understanding of the basic principles of aquarium lighting and the various methods by which they are presented to the hobby, we face the ultimate decision of what to buy for a reef system, and why?
The Light Manufacturers' Marketing Game
O.K., remember how I said that each company likes to tout its product as the savior of the marine community? Well, I can tell you that you will have equal success with fluorescents as well as PCs (Power Compact fluorescents), MHs (Metal Halides) and power stars (a differing bulb manufactured than standard MH). Marketing is nowhere more dominant than in this hobby.
The consensus is that if you have the disposable income to even THINK about setting up a saltwater aquarium or reef, then you have enough to plop down $495.00 for a powder-coat, German tensile steel light bar that looks like it came straight off the space shuttle!
Actually, for my first three years in the reef community, I used Ultra-Lume 75’s and actinic light tubes. When was the last time you saw Ultra-Lumes advertised? Not sexy anymore. The fact that they work is irrelevant. Marketing, remember? Ask the folks that own Cyclone skimmers about advertising vs. performance and you'll begin to see my point. Now please, don't get me wrong. I like my toys as much as the next person, but think of how many more you can possess if you keep the second most expensive addition to your marine set-up, under control. That's right, a VHO package isn't cheap! Metal halides are even costlier, not to mention that steel light bar I mentioned a bit ago.
Choose carefully and plan ahead. Look toward the day when you wake up and WANT to cultivate SPS (Soft/Small Polyped Stony) corals or the like. Unless you know that this isn't in your aquarium future, stick to standard fluorescents and spend the savings on upgrading or buying a great skimmer, not just one that you can afford now. Skimmers? Maybe a future article, but not here and not today. LOL! Right now I am going to have a serious discussion about using pre-manufactured light hoods for lighting a reef system, which is NOT a good choice!
Why You Shouldn't Use Pre-Manufactured Light Hoods
Let me start out by stating right up front that plastic, pre-manufactured light hoods are NOT acceptable on a reef system. Besides the obvious, the design limitation on using HO (High Output) or VHO (Very High Output) tubes, these hoods cover 95% of the surface of the tank. This leaves little room for overflow boxes, powerheads, hang-on skimmers, etc.
Also of serious concern is the restriction that a full enclosure at near-surface level creates on oxygen gas exchange. This is a biggie with me and should be with others as well. Reef tanks should incorporate "open-air" or have unrestricted access to the entire water surface area. Not only does this allow for freedom of movement for moving/adding and feeding, it also allows for the best gas exchange between the water surface and the room's atmosphere. If you MUST cover your tank top, use egg crate available at Home Depot and the like. This will allow for air movement, easy access for adding rock, corals and animals, as well as keeping those "jumping" fish from performing Hari-Kari onto your Oriental rug. Did I mention that plastic egg crate is just about the most versatile of all the accessories that a saltwater enthusiast can have? No? Well, shame on me! Not only does the egg crate keep your fish where they belong, it also acts as a support for your fluorescent light tubes!
The Pros and Cons of Using Metal Halides
Oh, please DO NOT use egg crate when running metal halides. Let's just say that I upgraded once upon a time from VHOs to a 250 watt MH and forgot to remove the egg crate. Honestly, it took me a few minutes of staring at the white stalactites that had miraculously appeared while I was at work before I realized that my lamp had melted the egg crate! Those metal halides sure get hot! This leads me into my next topic of discussion, the pros and cons of using metal halides.
If I seem to dwell on VHOs, there's a good reason. While Metal Halide (MH) lighting is the finest light energy source we have, and it can provide the right incredible intensity of light ideal for maintaining delicate to establish SPS corals, they create all kinds of other issues to the aquarist.
Metal Halide are essentially a very powerful incandescent light bulb. Touch a 100 watter in your living room lamp and you'll see my point. Now, magnify that to 175 or 250 watts and you begin to see the impact on water temperature. Maintaining water temperature at or as near to 76-77 degrees is problematic enough. Hang that heat-radiating bulb six inches above the water surface and watch your tank temperature climb, Climb, CLIMB...
Fans, chillers and building special hoods to accommodate MHs are but a few of the residuals that using these bulbs can create. If you are not willing to shell out $500.00-$600.00 for a commercial chiller, then using fans mounted at the water surface or in the hood are your only avenues of keeping the water temp within limits. Ever hear of the domino principle? Fans cool the water by evaporation. If you are replenishing a quart or two a day due to ambient evaporation, just wait till you kick that fan on! Doubling or even tripling current evaporation rates can be realized when using cooling fans.
One thing DOES lead to another here, doesn't it? Did I mention special hoods for MH's? Yep. A 12-inch MINIMUM distance from the MH bulb to the water surface is the rule. This allows some air movement between the bulb and the water, lessening the heat impact. Still gotta use those fans, though!
Using Power Compact Fluorescent Lamps
Actually, nothing more than a straight tube bent in half, compact fluorescent lamps deliver a higher concentration of light energy in a smaller space than standard-length tubes do. Their VHO nature gives them the ability to deliver the right amount of lumens in whatever color temperature (CRI, K., etc.) you choose.
I ran a 20 gallon long on 6-9 watt compacts for three years. One 9-watter is equivalent to a standard 75-watt incandescent, so you see my little tank was well illuminated! Yeah, I had SPS frags in there, too.
Most corals can be placed into three major categories: Stonies, (exterior skeletons), Soft, (no calcium based skeleton), and SPS's (Soft/Small Polyped Stonies). In Chapter 4 I discuss these three Coral Categories in detail, addressing their individual lighting requirements.
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