Light Track System, Electricity Savings, etc

[Origami]

The reflectors are lumenarc 3. They are 22" wide so roughly 4' of the 6' is covered by reflector. PAR is about 200 umol on a completely cloudy day. I am running these lights 13 hrs/day since sunlight is so variable and weak right now. On a sunny winter day, PAR is near 500-600 from the sun only. Summer day with no shade, par is near 1200. I am trying to aim for 500-600 max, with a 200 baseline. This seems to be working for about 2/3 of my sps, which have reasonably good color (some have excellent color). The other 1/3 are brown, mostly corals that would normally be purple. Most every colony is growing at some level, some quite fast, others slowly.

 

Thanks for the detailed answer, Justin. It's very illuminating!

 

In your case, it seems that your lighting is being used to augment natural lighting. In your greenhouse, you're lucky to have natural lighting because it provides most all of what you need. Here's a quick sketch of what I can tell from your numbers.

 

Your target baseline PAR of 200 umol/m^2-s, over 12 hours corresponds to a delivery of 32.14 moles of photons in the photosynthetically active band for a 4' x 10' (40 square foot or 3.72 square meters) area. (Recalling that Avogadro's constant is 6.02*10^23, your baseline delivery into a frag tank is equal to 1.93*10^25 photons.)

 

If I assume that the 200 umol/m^2-s is delivered exclusively from one lamp over a 4' x 4' (16 square feet or 1.5 square meters), then in 12 hours that lamp will put out almost 13 moles of photons. These, then, are distributed across the frag tank by the motorized track lighting. In the end, though, it's still about 40% of your baseline, or 16% of what is delivered by the sun on a sunny winter day.

 

That means the sun is providing the majority of your lighting needs which may not be the case for the OP. It's certainly not in my case where my display is in the basement. If I turn the lights out midday, it gets rather dark!

 

Many of our corals are dependent upon photosynthesis for a large portion of their energy needs. Photosynthesis is a process by which light energy is converted into chemical energy and is described in summary fashion as:

 

2n CO2 + 2n H2O + photons → 2(CH2O)n + 2n O2

carbon dioxide + water + light energy → carbohydrate + oxygen

 

Thus, light (photons) on the left hand side of the equation converts carbon dioxide and water to the sugars and oxygen on the right hand side of the equation. Given that CO2 and water are available in abundance and are not limiting the reaction, the light energy on the left hand side of the equation mediates (or regulates) the reaction. More light yields more photosynthesis (up to a point - this is a very general statement).

 

PAR and these numbers that come from it are relevant because, in a very real sense, we dose photons into our tank in the same way that we dose other additives. We control that dosage by varying the intensity (wattage and color) of the light and the dosing time (the time the light's on). These photons go on to drive the photosynthetic process outlined below (from Wikipedia). (Of course, we have to be cautious about how fast we dose, too. A brighter light over a shorter period may not have the intended result if you burn up your coral!)

 

In the OP's case, he's considering going from 3-250W bulbs to 1 bulb. This will decrease light (photons) into the tank by 2/3. I can't help but think that this will have some impact if he's relying upon artificial lighting for the bulk of his needs. Of course, this is just my gut feel. I'd love to see how this works out.

[ctenophore]

I have many days where I get basically zero from the sun. So the low par from the MH are enough to keep most corals happy. My guess is that with some always-on T5 supplements to act as the baseline PAR, the single MH will be enough.

 

Magnetic1, if you try this and find it doesn't work out for you, I'll buy the light mover from you assuming you get the agramover model with the built-in outlet box. That way you're only out the cost of the unistrut.

[magnetic1]

I have many days where I get basically zero from the sun. So the low par from the MH are enough to keep most corals happy. My guess is that with some always-on T5 supplements to act as the baseline PAR, the single MH will be enough.

 

Magnetic1, if you try this and find it doesn't work out for you, I'll buy the light mover from you assuming you get the agramover model with the built-in outlet box. That way you're only out the cost of the unistrut.

 

I may decide to, Ill need to lay it out in my head and see how this will look.

[Coral Hind]

Justin, That is a very nice offer.

 

I am still not thinking that the FTS is going to look right with a spot light in just one spot.

[Origami]

Hey, I found this very good article from Advanced Aquarist that you might be interested in. I think I may have read some time back when some of us were discussing the effect of photoperiod on growth. In case you're interested, it illustrates the concept of the daily light integral (DLI). Also interesting to me are the DLI measurements taken on a reef in Hawaii over different times of the year because they give you some basis for comparison. (30 mol photons per day per square meter in Spring and 16 mol photons per day per square meter in late Fall.)

 

The article also says that it is probably not necessary to match this in an aquarium because "Most 'common' corals saturate (that is, photosynthesis is at a maximum rate) at light intensities ranging from 200 to 450 mmol/m