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new tank plans, opinions wanted


finch6013

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I am theoretically planning a new tank for the future. I think I will be making a shallow reef using a marineland 70 cube. Tank dimentions are 30x30x18.

Or I might go with the 93g that is 30x30x20. Either way it will be in those general dimentions. Currently I am looking into how I will light the tank. The tank will be an sps only tank like my current solana. So far I am leaning towards a single MH in the middle with actinics around the rim of the reflector. Should I go with a 400W radium or a 250w radium? also what reflector would fit in those dimentions but still leave room on all sides for actinics? I think I will need a reflector that gives good spread.

Opinions wanted, How would you light the tank?

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I would be using a hood so as long as the reflector left enough room on each side i could figure something out. I would like to use a 250w but looking at my current tank there is no way a single 250 would be enough. I dont really want to run 2 250's because of electrical cost, bulb cost, and the extra reflector cost.

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The 93gal is 24" tall, and for that tank I'd definitely go with the 400W. On the 70gal, you might get by with the 250W. A good SLS reflector will give you even illumination over a 24" square. That'd give you room around the edges at the bottom for less light hungry LPS/zoas if you want any.

 

I'm thinking of doing a similar build, but with more of a mixed-reef loadout. I look forward to following your build.

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I humbly beg to differ...if any of you have ever snorkled in clear reefs, although they are clear, where the corals lie is not "400w" bright...I personally feel that it is totally unnatural to blast corals with "400w"...at least in a tank that isn't over 32-34 tall...

 

I've had 400w in my 135 and felt they were way too bright...almost too difficult to look at...I am always amazed at how well many "bright" light corals do in moderate to lower light...

 

I know it is a matter of personal opinion, but coral reefs are often overcast or rainy and corals don't get near as much light as we think they do...I personally think for shallower tanks, 400 is overkill...I'd humbly submit a request for 250 w Brandon.

 

DrMerle

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The 93gal is 24" tall, and for that tank I'd definitely go with the 400W. On the 70gal, you might get by with the 250W. A good SLS reflector will give you even illumination over a 24" square. That'd give you room around the edges at the bottom for less light hungry LPS/zoas if you want any.

 

I'm thinking of doing a similar build, but with more of a mixed-reef loadout. I look forward to following your build.

 

My build will be quite some time from now and its dependent upon a house that we are trying to buy.

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I humbly beg to differ...if any of you have ever snorkled in clear reefs, although they are clear, where the corals lie is not "400w" bright...I personally feel that it is totally unnatural to blast corals with "400w"...at least in a tank that isn't over 32-34 tall...

 

I've had 400w in my 135 and felt they were way too bright...almost too difficult to look at...I am always amazed at how well many "bright" light corals do in moderate to lower light...

 

I know it is a matter of personal opinion, but coral reefs are often overcast or rainy and corals don't get near as much light as we think they do...I personally think for shallower tanks, 400 is overkill...I'd humbly submit a request for 250 w Brandon.

 

DrMerle

 

Absolutely, the aesthetics are a matter of personal opinion but the PPFD numbers tell us that even a 400W bulb provides nowhere near the intensity of light that a coral reef gets from the sun.

 

At 10m of depth, the summer sun provides a PPFD value of 618 umoles/m^2/sec (this drops off to a PPFD of 436 @15m). A 400W Radium overdriven by an HQI ballast provides a PPFD value of 147 before bridging the air-water boundary (which, depending on the angle of reflectance, can drop the PPFD value by 10% or more) and penetrating any depth of the aquarium water.

 

The reason the 400W bulbs look so bright to the eye is because the ambient light in the room is relatively low. If you were to take an aquarium lit by 400W bulbs outside in the height of summer, they wouldn't look very bright at all (even here at out northern latitudes, it'd be even worse nearer the equator) -- in fact, I'll bet it'd look like there isn't even a light *on* in the aquarium. I know that when a shaft of natural sunlight strikes the edge of my aquarium, it is *way* brighter that the MH lights.

 

Using a 400W bulb isn't an unnatural blasting of light -- quite the opposite, it's providing significantly *less* light that many reef-building corals get. That's not to say we're mistreating the corals by under-illuminating them, 'cause I don't believe we are... they've very adaptable when carefully acclimated. But if you want anything approaching "normal" levels of coloration and growth (for typical SPS), even 400W of MH lighting isn't enough.

 

Check out these articles for more details and a lot of math (scary):

 

Underwater Light Field and its Comparison to Metal Halide Lighting

 

Facts of Light: Part 2

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