Canreef Aquatics Bulletin Board - Lighting, a beginner’s guide (part 1)

NO, VHO, PC, MH, URI, Phillips, Ushio, IceCap, Fulham, etc...
These are all terms/words that have been flooding our minds from the first minute we started to learn about our tanks, and the types of equipment to use on them.Although most are useful, some are just brand names and don’t really tell us much but needless to say, they have become associated with the talk we talk in the hobby.

I am going to do a series of write-ups on what I hope, I have become just a little knowledgeable in over the last 4 years of pulling my hair trying to figure it all out.

A little bit about my background first; I am presently employed with the Department of National Defense as a Marine Engineering Technician, and as well as mechanical theory, my schooling has included a fair amount of electronics, electricity, AC and DC theory, and instrumentation and controls. This is in addition to the regular mechanical, pipe fitting, machinist etc... training we receive. I do not claim to know everything but I do like to think I have a fair working knowledge of electronics and such as I have been doing some of it as a hobby and work for about 20 years.

Well here is Part 1, Fluorescent lighting.

What is Fluorescent ballast you might ask? The answer is nothing more than a current controlling device. The basic ballast is made up of a transformer (to raise voltage), a choke or winding (to limit current in conjunction with the tube) and a capacitor (to raise efficiency). So you ask what is the difference between NO, HO and VHO ballast, basically in a simple system it is the maximum current that the ballast is designed to output. This means that a ballast made for NO lighting will be able to put out a max current of 0.4Amps, a HO ballast outputs around 0.8Amps (also the same make up as a ballast for Power compacts), and a VHO is approximately 1.5Amps. All this doesn’t tell you how much power the actual tube consumes though as this is also a factor of the resistance of the tube. To make different wattages of tubes the manufactures build a specific resistance value into the tube its self, so that when this resistance is added to the resistance of the ballast you can then use the current to figure out the actual tube power output. Lucky for us this is labeled on the tubes and we don’t have to do the math.

Lately the big buzz is Electronic ballasts. What does this mean to Fluorescent tube users? Well basically they operate the same as basic ballast with one major difference; Where a normal ballast runs on a 60Hz frequency, an electronic ballast will take this and transform it into a much higher frequency, typically 20,000 Hz or higher. So why is this important? Well, a Fluorescent light basically operates by turning on and off very fast. A normal ballast does this 120 times a second or twice the Hz by running the tube at 20,000Hz you are turning the tube on and off 40,000 times a second so you get a much more constant light.

So what are the benefits from running electronic ballasts?
1, you can use smaller solid-state circuitry allowing for smaller and lighter ballast.
2, since the tube is switched on/off faster there is less cooling in-between cycles allowing a higher thermal efficiency and also less flickering of the lamp.

And 3, the operating cost of the ballast is improved by 10 to 20% and actual tube output is increased by 10% due to the higher frequency for the same power input or the tube can be run at 10% less power and give the same light output.

There also are some disadvantages to electronic ballasts and some of them are: higher cost, more electrical interference from the higher frequencies depending on the design, and they require a larger current on initial start up than regular ballasts.

Other words you hear are power compacts and T8, T12, T5 and so on, the T# relates to the size of the tube, the actual physical diameter. A T12 is a 1.5” dia., T10 is 1.25” dia., and a T8 is 1” dia. The thinner you make the tubes the more intense they are for the same power so this is why a 32 watt T8 tube will give out the same amount of light as a 40 watt T12 tube.

So how does this all apply to the tanks, well one of the first choices you have to make is how you are going to light your tanks. Are you going to use florescent for main lighting, for actinic or not at all? The 3 choices are all valid. If you have a fish only tank, don't waist the money on VHO, PC, or MH. Just use NO for both daylight and actinic. After all in a fish only it is just for looks.

If you go predominantly low light you might consider using a mix of NO (for actinic) and VHO (for daylight) or all VHO, or even PC. In a medium to high light set up you could use NO, VHO, PC, MH or any combination of them.

Which ever you decide, do your home work and be realistic first, you might end up spending more saying I will start with VHO and upgrade to MH later when I get more light demanding corals, take it from me I upgraded my lights 4 times because I had to try PC’s and overdriven NO, and this and that but I ended up settling on MH for daylight and VHO for actinic, and I would have saved about 2000.00 if I just went to MH/VHO to start with.

The next Part in this series I will talk about MH and the different options that are out there.

Steve