SolaTubes for reef tanks

[Surfcaster]

Lets keep this thread going, I am thinking about going with the natural lighting (solar tubes) instead of MH.

Can we see some updated pics from you soar tube users.

 

[kysard1]

The thread died because it won't work unless you use huge tubes and live in the desert. The wattage comparisons are to incandescent which is 10% of Metal Halide. Won't work. Would be better off bulding a slanted mirror top and put your tank in front of a window but then you would run a chiller and still be losing on the electric bill.

 

[AuroraDave]

The thread died because it won't work unless you use huge tubes and live in the desert. The wattage comparisons are to incandescent which is 10% of Metal Halide.

Kysard1--
Those are the stats that we have been trying to get.
Where did you get the readings and how did you measure it?

 

[SAT]

I think Kysard1's dismissal of the concept is a little harsh. Back in April I compared light levels by putting a photographic grey card on top of the tank, checking the level with my camera meter, and repeating the experiment outside. The camera meter showed no difference.

A camera meter uses a logorithmic scale, so it takes a substantial (say 20%) difference to register. So, let's say I got 80%.

According to Adey's charts, late April sunlight isn't much different here (SE Pennsylvania) than in many areas of the tropics. It's actually higher in May/June/July. However, in December the sun only delivers 50% and the tubes are less efficient at collecting what is delivered. The lower sun angle means less light enters the tube in the first place, it bounces more times, and it leaves the tubes at an awkward angle. Thus, I think the tubes will supply the light I need for about 6 months of the year (equinox to equinox) but will need significant supplementation during the winter.

So Kysard1 is right that these tubes aren't the whole answer. However, even with supplementation, the tubes will save a lot of electricity. I'm estimating a 60% savings on the average for myself. Plus the tubes generate a lot less waste heat and deliver a high CRI -- even after the light bounces around in the tubes for a while.

 

[kysard1]

The camera meter is probably not the best for this. I use a GE Ftcandle meter on the tubes and the only version which was close to a 150W MH was the 21" version with only a 6 ft tube (no turns) and a very bright SE PA (small world York here) sunny summer day. Sorry but who would want 3 or 4 close 21" holes in their roof? I think a better method could be made using a south window if you could engineer around the heat

 

[Surfcaster]

It sounds like sloar tubes are best used to suppliment the artificial light, there by using less electicity and giving our creatures at least some natural light. I especially think the moonlight the tubes bring into the tank is very benefitial to coral spawning. So there is a practical use for the tubes.

 

[mfranklin]

I got to this thread through another thread I started so I am bringing it back to life.

SAT do you have any more updates or pics?

 

[SAT]

SAT do you have any more updates or pics?

Still have a ways to go. Finishing the rest of the house has taken priority over the aquarium. The tank has water in it, but only to prove the plumbing and encourage any settling to occur before I fill it for real. We'll move in January. I doubt I'll have any coral in it before spring.

 

[scot]

SAT

How does the intensity of the light look with water in the tank?

 

[SAT]

How does the intensity of the light look with water in the tank?

Scot, it looks rather dim right now, but that's not surprising considering the mitigating factors: It's right at the winter solstice, the sun is actually below the tips of the trees (which mercifully don't have any leaves), the low-angle sunlight has to do a lot of bouncing in the tubes, the tubes currently have a light coating of construction dust, and the water isn't clear enough to see the length of the tank!

Ask again in a couple of months.

 

[scot]

SAT,

Your not making my decision any eaiser, but thanks for being honest. I plan on supplementing with 1 20K 400w in the center and 2 140w VHO actinics. I may have to trade the 400w for two 250watters. My goal is to try and keep the power bill down but still have lots of light.
I still think there's lots of benifits to the tubes even if the intensity's not up to par (lol). The natural light, constantly changing intensity plus the natural moon light and cycles. I'm going to buy a tube to experiment with after the holidays.

Please keep us posted
Thanks
Scot

 

[SAT]

Scot,

I won't comment on how many Watts your system needs, but I basically agree with the sentiment. At best, I figure my setup will deliver adequate light during the Summer and half of what I need during the Winter.

 

[andrejka]

SAT,

Any progress? You should be getting enough light now
Seriously, I hope you didn't give up the idea. Bought any corals yet?

 

[skylsdale]

Is ANYONE ever going to post pics??!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[SAT]

...keeping me waaaaaaaaaaaaaiting... Wow, this thread has a life of its own!

My tank is still cycling. The nitrites have been hovering at 1ppm for about 3 weeks and I'm really getting tired of it! :hammer: Once they clear I'll add the next batch of live rock. We'll see about the primary inhabitants, like corals, after that cycle completes. Then we'll see about some pretty pictures of corals in sunlight. I'm trying to do this right, so don't hold your breath.

I measured the noon-time light intensity last week, a few days before the equinox... it was about 5-10% of full outdoor sunlight at the sand bed and about 20% at the canopy. I was pleased to see nice glitter lines on the bottom of the tank. I figure that's enough light for deep water species, but will need supplements for anything else. Maybe once I clean the dust out of the tubes everything will look better (it's an ugly task and I've been procrastinating ever since the weather improved).

The good news is I managed to control the air leakage from the RCSD. When that sucker fires, everything in the tank waves back & forth. :rollface:

 

[andrejka]

Thank you for the update, Stuart!

I won't let this thread die until we see some pics...

 

[H20ENG]

Glad to hear of the progress! We want to see your RCSD, too!
Chris

 

[buff1]

I looked into this solar tube idea about 3 years ago and couldn't find any decent info. I'm thrilled to see the idea actually being tested. I had a couple of thoughts. First, if you had a south facing pitched roof and the dome was tilted to match the slope of the roof, I would think the amount of light entering the tube would increase greatly. Second, I would think you would benefit by bringing the bottom of the tube as close to the waters surface as possible while still allowing access.

I also followed a thread about fiber optics over on reefs.org. I think there is a lot of potential there, but it would almost certainly need a sun tracking collector on the roof, which adds a lot to complexity and cost. Still, the potential is very exciting! I love this stuff, let's keep this thread going!

Also, a word of caution about going cheap on the solar tube. I had a solar tube installed in my pantry when our house was built. It was only a 10" and we got it at home depot. I think the reflectivity is much lower than the high end ones mentioned here because it is quite unimpressive. It lights the room enough during the day that you can find what you need, but I would estimate that for most of the day (ie: the sun not directly overhead) it is about the equivalent of a 25 watt bulb. This is not a light meter measurement, just my best estimate.

 

[SAT]

buff1,

<img src="/images/welcome.gif"><br><b><i><big><big>To Reef Central</b></i></big></big>

Good points. I think you are right that angling it would be more efficient. The manufacturers' instructions generally say to point the tube straight up. Some models don't allow bends, so this could be an issue for them. You may also find the dome seal will allow leakage if it's not vertical (my domes are sealed with brush-style weather stripping).

I also agree the tubes should come as close to the water level as practical. The light doesn't normally come straight down the tube, so the more distance the less light you get.

 

[SAT]

OK, time for some pictures. I took these this morning around 10:15AM, about 2-3 hours before peak sunlight. The total tank size is 96x24x30H (nominally 300G), but if you take out the hidden areas & sand bed, it really more like 78x24x24H (about 200G). It's lit by three 21" skylights and 320W VHO (URI, one actinic one 50/50). When the sun is out, the VHO contribution isn't obvious to the eye.

I'm using a Canon A60 balanced for sunlight, with no flash. I use Photoshop to adjust the contrast levels and reduce the saturation (the camera is overly color sensitive to my eye).

Here's the center section of the tank (the remainder is mostly open and doesn't photograph well).