1 more lighting thread with some questions

[Canadian Man]

So I need some opinions.
On my 90g mainly sps now tank(48x18x24) I have 2 Iwasaki's mounted aprox 12" above the water surface.

Can any of you see any benifits to adding a 175 w 10000k bulb inbetween the existing iwasaki's?

My other thought is because of the crossover of light across the tank would the corals in the center or middle 36"(aprox) be the only ones to benefit from the added light?
What I mean by this is if one of my halides is on and the other is off the light crosses over more than half the distance of the tank.

Any thoughts on this??
Thanks All :D

[StirCrazy]

you mentioned that your brace is made of acrylic now.. that might be a problem with the MH right over it.. might soften it and cause it to fail..

I can't see that you would even notice it against a couple of iwasakis.. it might brighten up the middle a little bit.. but if you wanted a even look throw an aditional iwasaki in the middle :wink:

Steve

[Canadian Man]

Well I figure at 12" above the brace it wont be much of a problem.

My whole idea behind this was to increase the light a little in my tank and maybe get a bit better color out of the sps.???

Anyone else???? or is this just a crazy Idea?
Yes part of my reason for doing this is all the other areas of my tank are fully tinkered and I NEED another project to work on. :? :lol:

[rossb]

Some old dead guy once experimented with light and water. Much was learned and it's all really boring. Two points come to mind that in part answer your question. First of all at the boundry between light and water a portion of the light is reflected. The amount that is reflected can be calculated using the sin of the angle of incidence ( or something like it). Basically the amount of light that enters the water is decreased as the angel increases. When light enters the water directly below it very little is reflected and can be said to be more intense.

The next most boring thing is what happens to the intensity of the light as it passes throught water. If I recall the intensity drops by about 50% in the first 10 cm's, and then much more slowly afer that (60% at 20 cm to 30% at 40cm).

So adding a light in the middle of the two existing would increase the intensity across the tank, and especially directly below it. So if this is what you wanted to do...

[AJ_77]

Here's an idea: for your next project, build a simple piggy-bank. Label it "Radium 400s" and start dropping your tinkering funds into it. Much better. :)

Alan :D

[Canadian Man]

Here's an idea: for your next project, build a simple piggy-bank. Label it "Radium 400s" and start dropping your tinkering funds into it. Much better. :)

Alan :D

That's a great Idea Alan! I have allready started that fund saving in my amarula tin!

I think this is what I was ultimatly thinking to do but we will see.

Thanks ross for the info. It was rather boring though :wink:

[Delphinus]

That's funny, I kind of have that same project going right now, except that I keep raiding the piggy bank for other things .... like .... Christmas presents ....

[BCOrchidGuy]

rossb is sooooooo right, I grow orchids, betcha didn't guess that. While searching for a MH for my room I was very very suprised to find out how quickly light intensity drops off. When a MH bulb is rated for say 40,000lumens, that is how much light is thrown over a 1sqft area 1 foot away from the bulb. At two feet the light will have approx, 1/2 of the intensity, at 3 feet, 1/4, at 4 feet, 1/9th... that is in air, remember water is alot denser than air so ..... anyway.... ross is right, if you can afford the $$$ I would add the other light, just make sure you keep an eye on that brace and see how hot it gets.

[Canadian Man]

Thanks Orchid guys!

I think I may do it. I basically have all the part except the socket and reflector. So it's not going to be too much to add it, another $75 for a socket and reflector + of course the electricity each month but when it's as high as it is I dont worry to much any more. :roll:

In the mean time I will save up for the radiums :wink:

[BCOrchidGuy]

You can always move to BC, electricity is 5 cents/Kwh here... at least in Burnaby it is.

[Jack]

I would add a 20k Radium, I have seen tanks on the net that use 65k saki's with 20k radiums w/no actninic at all and it looks awesome. Start saving!

[Delphinus]

Here are my thoughts

Personally I think both ideas of adding another light, and lowering the existing lights, have merit. If reality wouldn't keep getting in the way, I'd have more lights in my canopies too (but since I already have 5 halides on the go as it is ..... did someone say "power bill" ?? Trust me, my power bill is bigger than yours any month!!! :P )

I personally feel that a mixture of bulbs yields the fuller spectrum than any one bulb type could provide. Where one bulb may be weak, another may be able to "pull up the slack" so to speak. The only thing is if bulbs have a vastly different colour to them you may get uneven colouring in your tank. When I first went into halides I had one side 14000K and the other 10000K so I could see what I liked better. The unbalanced look, while I was decided, was striking. It's very unnatural looking.

10000K is theoretically not all that a huge contrast (not as bad as say 14000K or 20000K). So a supplemental 175W/10000K sounds like a good idea.

Since we're talking about supplemental light, you may wish to consider the light without a reflector (or maybe just a flat reflector above the light), so to spread out the light. As Ross points out the further away from the light, the less light going into the water at that point, but I don't think that's a concern in this case because 1) this is just to supplement a little bit, and 2) it will help to "blend" the light zones somewhat. At any rate it is something you can try first, you can see what you think, and then decide whether to spend the additional $75 on a parabolic reflector.

Also, about lowering the lights .... again as Ross pointed out (but it was sooo boring to read :P ), the intensity falloff is exponentially proportional to the distance of the light source (note to you grammar nit-picks ... I said the "falloff" is exponentially proportional, which should be the same as saying "intensity is proportional to the inverse of the exponential distance" ... ow my head hurts never mind). If I could get away with it, I'd have my lights 1" above my water surface!! If I pay $10-20 per bulb per month, I feel better knowing that as much of that light is "useable" rather than being discarded by bouncing off this or that, cover glasses, attenuation, etc. etc.

Anyways just my $0.02

PS. Adding another light is going to stave off your boredom for about .... well, 2-3 hours, tops. So don't put a lot of stock in this to help you deal with your fidgetiness .... ;) :P :)

[Canadian Man]

Thanks Tony! I always like your long rambling posts :wink: :P :D
Kidding....They are very informative.

That's a good idea about adding it with out the reflector. Partly, because I have all the stuff to do it that way and the other is that it saves me $75 to put toward my radium fund :lol: .

I would like to lowwer my lights but it would be alot of work,
1. I have to first lower my actinics, which is the most difficult part and then lower the halides which is actually the easy part.

Anyone want to come help me redo my hood one evening????lets say around 10:30 pm, as not to disrupt the lighting periond too much :roll:

[Delphinus]

Well you know I'd be happy to help out with a set of hands (clumsy as they may be) anytime, as I'm sure most of us would also be... Anytime I'm not fidgeting, er ... "adjusting" one of my own setups that is. :)

Could you mount two of the actinics on the front and back sides of the hood? That way you only need to mount 2 bulbs laterally, and maybe then you have enough room to lower your reflectors?

Last but not least, if you need a socket without a reflector, I suggest a place like QuickGrow (just a block or two south of Wai's on Centre St.) or Bumper Crop (up by Pisces), they have a threaded socket that you can use to mount using galvanized piping, this is what I have used (with the exception of the forthcoming 72g hood of course). If you need to look at them to get the sizes and stuff ... well ... you know where I live .... :)

cheers

[Canadian Man]

Thanks Tony!