PAR Measured - UNS 30C Sunlight desk reef

[Mr.Gone]

I'm going to attempt a nano reef tank in a UNS 30C that gets direct sunlight from a south facing window. My Original plan was to use sunlight exclusively, but after some PAR measurements thats not going to be a realistic goal.

I want to see how much trouble the sun can cause and see what ways I can control lighting. My plan is to run the tank coral only for as long as I can (with other invertebrates/clean up crew). I've committed to getting a fish IF the rest of the tank works out, otherwise it will be a fishless tank (though a fish may come in handy to provided nutrition to the corals...)

The plan is cautiously optimistic. I've had difficulties with keeping reef tanks before but in my case I think that's due to the tank being in a room I don't often spend time in. That particular tank is on an upswing now though, and that has given me the momentum to start this tank in my bedroom where I will be unable to "out of sight out of mind" all of my issues. Here is my first ever saltwater tank at 1.5 years old:

To manage the light I've left room for the window blinds behind the tank. I can adjust the angle of the slats to block direct light but the diffused light coming off of them still looks bright. I don't know exactly how daily/seasonal variations in light intensity will impact the corals, but I expect they're biologically equipped to adapt to some degree.

With introductions out of the way, I'd love to hear the wisdom of the crowd. Let me know what corals you would like to see in this tank and if you have experience running a tank like this your input would be invaluable.

Thanks!

 

[Troylee]

Might be sustainable for soft corals at best.. I think you’ll find you need more light unless you use a solar tube or something to magnify the sun.

 

[14 foot reef]

Measure Par, please report back.
How long has this been set up ?

 

[CHSUB]

Lots of examples in Miami with people doing it successful. Might have less intense Sunlight in Long Island? Not sure but I think this is how the Ocean does it…. Not a fan of the filter, unless you plan on cleaning more than weekly.
Good luck and well done.

 

[Mr.Gone]

Measure Par, please report back.
How long has this been set up ?

The tank was filled just a day ago, if/when I measure PAR I'll be really thorough and document everything to share with the community.

 

[14 foot reef]

The tank was filled just a day ago, if/when I measure PAR I'll be really thorough and document everything to share with the community.

You may entertain blocking all sunlight till you get through a full cycle and a really good bio built up with live sand, live rock or seasoned bio material.

This set up may quickly lead to a rough start with the ugly stage.

 

[Mr.Gone]

Lots of examples in Miami with people doing it successful. Might have less intense Sunlight in Long Island? Not sure but I think this is how the Ocean does it…. Not a fan of the filter, unless you plan on cleaning more than weekly.
Good luck and well done.

Thanks for the comment! Believe it or not I share your sentiment about the filter. I am currently using a larger one on a freshwater set up and the maintenance has been much less than any HOB I've ever used, that said this particular canister is much smaller so only time will tell. Because the tank is small and I want it to be under stocked I'm hoping that I'll have some flexibility with equipment.

 

[Mr.Gone]

The tank was filled just a day ago, if/when I measure PAR I'll be really thorough and document everything to share with the community.

You may entertain blocking all sunlight till you get through a full cycle and a really good bio built up with live sand, live rock or seasoned bio material.

This set up may quickly lead to a rough start with the ugly stage.

I'm expecting the uglys to boom and then bust pretty quickly. The high amount of light from the sun will cause the algae to starve themselves, the question is will the corals experience the same effect. In my opinion if the tank cycles in the light, hits ugly stage, and then recovers in the light, the resulting microbiome will be the best suited for the tank I want (but this depends on those beneficial microorganisms making it into the tank). My original plan was to use ocean live rock exclusively and just let it ride to see what came of it in the sunlight, I wouldn't have even added corals, but I couldn't justify the costs for a tank so small. I do have tank cycled rock though so I'll use that to seed the tank.

 

[Mr.Gone]

PAR report coming soon, just want to organize the numbers to make a better presentation. I have data from summer solstice (presumably the max intensity of sunlight) and from today.

Tank hasn't changed much but I used it as a temporary holding tank for some cleaner shrimp, just a glimps of what could be...

 

[Mr.Gone]

Here is the PAR measurements I took in August with direct sun on the tank:



I also took measurements with the window blinds down and completely closed. In that case I never measured PAR above 50. If I opened the blinds but adjusted the angle of the slats to block direct sunlight, the scattered light created 80-150 PAR in the tank. Now that I have these measurements I'm convinced that my original plan would not have worked. One way or another I'll have this tank up and running - I'm not out of options. Having some control with the blinds means I will still try to keep it on my desk, but I do need to introduce artificial lighting and then the tank will have to run off of that instead of sunlight.

Basically I have to fight the sun to keep this tank where it is, which is a bummer, but I suspected that would be the case.

Also, I haven't seeded the tank yet. I'm still considering how I may do this, whether I introduce some rubble rocks from my other tank or something from my LFS or spend the money on something maricultured. That said, I haven't had any issues with slimes, algae, or other pests yet. That will be the real test for this tank, to see if instability in the lighting is enough to exacerbate these issues to the point of failure.

Anyway, the light I chose for this tank is an amazon knock-off, the SMARTFARM 60 Watt Reef Light. I choose this light because it came with everything I needed for a fair price, but its turned out to be more overkill than I expected. So far it works like its supposed to, nothing to complain about really, except that the programing interface is a bit tedious. I could also complain about the mount being ugly on this tank but that's not really a fault of the product, I am considering getting creative and making my own mounting solution. I bought the light back in late November.

Yesterday I was finally able to measure the PAR output of this light. I have it mounted at ~3in from water level (admittedly very close) and off-centered toward the back of the tank. I first measured the SPS and LPS presets, then my own settings which were based purely on a guess and appearances:

Since I set up this light I had it on the same settings as in the bottom left PAR map. When I read the PAR meter I was totally caught off guard by how much PAR was in this tank. I placed a frag of GSP in 480 PAR and I didn't even realize... yikes

Eventually I tuned the light and settled on 10% for each channel to get the desired PAR. I'm targeting a mixed reef range since I haven't made up my mind as to whether or not I'll try SPS. In terms of spectrum, I have no measurements to go off of, only the manufacturer's specification. I figured if I left every channel at the same value then the spectrum shouldn't have changed - trusting the manufacturer on this one.

Let me hear what you think.

P.S. I have a graph with PAR intensity vs power and I could share that if people want to see it, just haven't gotten around to making it nice looking. Basically I plotted the trends in the maximum, high, low, and minimum PAR positions at each power level, and there is a remarkably consistent linear relationship that I could use to calculate PAR for a given power level - which I can measure with the smart power strip I'm using.

Thanks for reading!