Aquarium lighting article (PC lights)

[cfockler]

It is suggested by various manufacturers, that a 55 watt power compact bulb produces as much light output as a 95 watt VHO tube.

In this hobby, I've come to learn that manufacturer claims are misleading and sometimes outright deceitful. I notice that you didn't explicitly support this claim in your article.

Is there any evidence (lumen/lux readings etc) to back up this claim?

Although, I have not had extensive experience with power compacts, I have used 55 watt 6700 Kelvin bulbs over one of my tanks. The light was very bright, however, the fixture was very warm when compared to the VHO tubes that I used on that same tank afterwards.

Did you switch back to VHO after trying PC because of the heat problems or some other reason?

Can you grow the same general corals with PC that you can grow with VHO?

 

[Doug]

Hi Clint,

In this hobby, I've come to learn that manufacturer claims are misleading and sometimes outright deceitful. I notice that you didn't explicitly support this claim in your article.

Is there any evidence (lumen/lux readings etc) to back up this claim?

You are very correct. It seems that there are manufacturers that make claims that are somewhat exaggerated or worse not only in our hobby but in many other areas.

The supposed light output increase has been discussed online and even on some vendors sites but I was unable to find information that supported those claims of the increased amount of light output. I did not want to support those claims without data to back it up but I do know that many hobbyists have had success using PC lights over their reeftanks.

Did you switch back to VHO after trying PC because of the heat problems or some other reason?

Can you grow the same general corals with PC that you can grow with VHO?

The heat was one major issue but the other issue was the look of the tank. The PC's did not give the same glowing look that the VHO tubes did over the tank. The color was a very stark white but it did look bright to my eyes. The corals in that tank did grow well and I am sure that they would have continued to grow but I was not happy with the look. I wanted to add a second fixture that tank but with the increased heat from the one fixture, I was afraid that I would not be able to cool the tank on very hot days.

I am sure that the heat would be easier to deal with in a retrofit open design but I did not have the interest to do so and felt that the VHO was a better choice since I had success with them previously.

I have used some lower power PC lights over a small 10-gallon tank and did have good success with coral growth. I had 2x27 watt 6700k lamps along with 2x9 watt blue bulbs and the soft corals grew well along with a couple of LPS corals.

To answer your question, I do feel that you can be successful growing corals under PC's and also know of a couple of people who use them exclusively over their propagation tanks.

Doug

 

[cfockler]

Thanks Doug,
I guess that explains why VHO seems to be more popular on the larger tanks where space is not as much of an issue.

I now wish I had gone with VHO when I setup my first tank (75gal) earlier this year. My tank temp is at the upper margins of natural reef temps (85 to 87 degrees F) and I'd prefer to keep it in the lower 80's. It's probably not too big of a problem considering it is summer and it won't likely get any hotter than it is now.

 

[lucayale]

pc lights for a 75 gallon tank

pc lights for a 75 gallon tank

hi Doug.
I write you from north italy.
I've bought an hanging lamp with 3 pc 55 w lamps and 1 8 watt actinic.
My tank is a 75 gallon that follows the berlinese method.
Do you think that i've made a good choice?
Is this system of lighting adequate only for soft corals?

Luca

 

[Doug]

Hi Luca,

I do not think that there are any "bad" choices when it comes to lighting unless there is not enough intensity or proper spectrum to satisfy the needs of the corals that we keep.

With that in mind, it is somewhat hard to answer your question without knowing a little more about your tank. Is your tank the standard 20 inch tall 75 gallon or is it a taller design? Are there any particular soft corals that you have in mind? I have found that some soft corals did very well under the PC's that I used where as others such as xenia did not do well at all.

Please try to give me a little more information and I will help as best as I can.

Doug

 

[lucayale]

thank you Doug for answering quickly to my questions.
My tank has this size: 90x55x55 cm. So it's about 20" deep.
In my intention I'd like to keep corals like actinodiscus, palythoa, sarcophyton, lobophyton, clavularia, zoanthus, sinularia and maybe in places near the surface corals like anthelia and some lps.
The biological filter is made by 110 pounds of live rocks.
The amount of light is 170 watt.

Ciao!

 

[Doug]

Hi Luca,

I am so sorry that I did not reply sooner. I have been out of commission for a while.

The corals that you want to keep are fairly low light corals but you might have to keep many of them near the top of the tank and have to watch them closely.

I have a 55 gallon tank which is similar in size, around 20 inches tall, with 210 watts of VHO light. I am keeping many of the corals that you are interested in but I have had issues with LPS that were placed in the lower area of the tank. They were living but were not thriving and growth was very slow to none.

One thing about corals and light requirements is that many corals will live in lower than optimum lighting conditions but they will not thrive. I have found that some of the corals that I keep under lower powered VHO grew very slowly but once I moved them to my tank with 400 watt metal halide bulbs they grew very quickly.

I am not saying that lower light systems are unsuccessful but if you notice that your corals are starting to decline addition light might be needed. I am sure that good placement will be a very important part of the success that you have.

Doug