Lighting question

[spiderpig]

I've been reading and reading, but I'm still a bit stymied about lighting guidelines. Bare with me on this...

In photography there's the concept of neutral gray. The basic idea is you shoot a neutral gray card (18% gray) with your equipment while adjusting various parameter, f-stops, film speed, etc. The goal of being to find the combination of settings for your equipment that can perfectly dial in neutral gray. Once you learn how "far off" you equipment is, which all equipment is, you compensate for it.

If the goal is to get the right radiation for the species in the tank, why can't their be lighting "gray cards?" Physics is physics. SW has a well defined acceptable range. The same with water temperature, etc. It seems like someone should be able to state that a new MH @ 10K 10" off the water with these water parameters typically produces XXX radiation at 10", YYY radiation at 15", etc.

I realize that bulds vary by brand, but that's the point. If there was some reference point then people could say that brand A's bulbs run 10% below the reference, while brand B is 20% above.

It seems like this would allow you to get into the right ball park for your species, and then let you fine tune with lamp height, specimen placement, etc. From everything I've read, the debate seems to revolve around types of light, rather than radiation at depth. And too a noob like me, it seems like people just light the hell out of their tanks and hope for the best.

Or...I'm completely missing the point, which is more than likely.

Thanks

 

[moortim]

I think part of the problem is that aquarium lighting is still a developing science. You mentioned that "physics is physics" which I interpret to mean that there are some concrete laws controlling the subject. The world of physics is drastically changing and is filled with as much debate (probably more) as aquarium lighting; it has just been around a long time so physicists have established some ground rules that do not change. The same is true for lighting a reef tank, we know that corals require light, we also know that some corals require more light than others. The discovery part of science comes into play on just about every other part of lighting. Subjects such as how to measure the light or exactly how much light do you need for X coral are still being learned about.

My point is that you are now delving (along with the rest of us) into a developing science that still has a huge amount to be learned about it. The more we progress, just like general physics, the more ground rules we will develop to help us understand the lighting needs of our animals. Until we find a standard to compare all lights to there will still be a huge amount of trial and error along with lots of bulb comparisons.
I think that is part of the excitement of reef keeping, there is a good chance that any one of use armchair scientists can find the answer to one of the questions that currently puzzle everyone but it will require lots of study and experimentation just like Newton went through.

Tim

 

[burning2nd]

I hear ya... and i understand...

 

[roblou]

Hi spiderpig: I think part of what you are talking about has already begun in our hobby. Check this website out: http://www.reeflightinginfo.arvixe.com/#

The author of that site has been collecting MH lighting data since 1998, with data for over 900 lamp/ballast combinations. There is a lot of data available on that website, including spectral plots for different lamp/ballast combos. But, what you won't find is the 'reference point' you mention.

I'm not sure whether we will ever come up with a 'reference point' that everyone agrees is correct. I think the lighting requirements are quite a bit different for different types of livestock, so what is the 'perfect' lighting for one species very likely is not the 'perfect' lighting for another.

IMHO, this is where personal experience and word of mouth from others become very helpful factors on what lighting is going to work best for your particular setup. Which leads us to sites like RF, where people can ask a question and get dozens of answers/opinions .

hth,
rob

 

[moortim]

And too a noob like me, it seems like people just light the hell out of their tanks and hope for the best.

Thanks

I was thinking again about this and remembered another tank I saw on here (I think) a while ago. The tank was out in a sunporch with a glass ceiling, for most of the lighting cycle it was lit by a generous amount of 400 watt MH lights which we would all say is definitely adequate. During the height of the day the tank was lit all naturally, by the sun. When the sun was on the tank you couldn't even tell the MH bulbs were on, it was so bright. I think that our best attempt to imitate the sun falls so far short that it is pretty difficult to have too much lighting over a tank compared to the real thing.
Of course there are other factors I did not consider here such as water depth ect. but I think the point still stands.
Just a thought

Tim

 

[Herefishyfishy]

Tim, exactly. One can look directly at a 400 watt MH, but don't try doing that to the sun!
I have used a very bright diving light. Really lights stuff up. In full sun in the ocean, can't even tell if it is on! The average tank is not even in the league of sunlight-wannabee. We do our best with the resources we have or can afford. Bali type mariculture has almost any tank beat to heck!