Lighting for very tall tank

illumnae

New member
Does anyone have recommendation for lights for an extremely tall tank, about 40-48 inches of water height? I just need to be able to see the fish in a fowlr setup, no need to keep any corals alive.
 
I have a 36 deep, and Ecolabs Radion unit does it, but they are, however, coral gear, and are spendy.
 
I did consider t5 and mh before but prefer led for controllability.

Good to hear that radio's work at 36". How dim is it at 36"? Light dropoff is exponential in water right? Do you think it would be strong enough for another 12" of water height? Given that height penetration is about the power of each individual led and not the spread, do you think even an AI prime would do the trick given it uses similar wattage led diodes but just with less of them?
 
Light dropoff is exponential in water right? Do you think it would be strong enough for another 12" of water height? Given that height penetration is about the power of each individual led and not the spread, do you think even an AI prime would do the trick given it uses similar wattage led diodes but just with less of them?
Depends on how you look at it..
A "panel" is not a point light source nor is it shining into "free space"..
It can be quite linear in certain ranges..
Examples (planted tank bulbs)
PARvsDistT5VariousLights.jpg
 
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Sorry I'm not very good at math, but doesn't the curve show it's exponential? Linear dropoff would be a straight line?
 
Extreme depth like that will want an over abundance of LEDs or a pretty dense MH array. There's nothing that says that you can't combine the two, but digging down 4' takes some intensity. LEDs are great for spot intensity or medium spread. MH is great for spot intensity and pretty good for spread. I don't have any experience deeper than 24", but I'd imagine you're going to need a lot of energy to get 4' down, no matter what lighting type you use. 400w metal halide with LED or T5 color supplementation would be my best guess for the best solution. The 400w MH could be replaced with LEDs, but your going to need at least 2x the fixtures that you'd need for a 2' deep tank...probably.

I've never tested this, but I've had a a 2' deep tank, MH, T5s and LEDs on it. Getting double the penetration would have been bat excrement crazy compared to what I had over my tank.
 
Sorry I'm not very good at math, but doesn't the curve show it's exponential? Linear dropoff would be a straight line?
Yes but I stated in ranges..
The intensity of light radiating from a point source is inversely proportional to the square of the distance from the source; so, an object (of the same size) twice as far away receives only one-quarter the light in the same time period.

so let's take the ATI at 15 and 30 inches
138 @ 15" so should be 34.5 PAR at 30"
Chart says 60.....almost 2x the expected.

isqrr.gif


Also like this (see green lines on brown curve) Like the slope of the curve at different ranges:
error2.JPG



See tanks don't exactly let down-welling light out that easy..;) unlike free space so it throws off the calculations.

PARdataSept2016RudySloup.png


Take reading at 12" and divide by 4.. see how well it matches par at 24"

Maybe I'm looking at it the wrong way but point is we have tanks that behave more in a linear fashion than log BUT each has errors....
If you use 6" and 12" the PAR is more 1/2 than 1/4.. ;)

1/4 of 45 = 11.25 Measured.. 21 ect. ect..
go bigger..
6" 12" 24"
45, 11.25, 2.81
real;
45, 21, 7
1/2
45 22.5, 11.25

suppose it's sort of an odd way to look at it..;)
2x the distance 1/2 the PAR..... Linear probably isn't THE correct term..just smoother than expected.
 
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Inverse square law?

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For example, the intensity of radiation from the Sun is 9126 watts per square meter at the distance of Mercury (0.387 AU); but only 1367 watts per square meter at the distance of Earth (1 AU)—an approximate threefold increase in distance results in an approximate ninefold decrease in intensity of radiation.
3 squared = 9..inverse 1/9

2x distance = 1/distance squared =1/4

Instead of losing twice the PPFD at twice the distance you lose 4x the "PAR" (PPFD)
 
Lol I thought what you were explaining sounded familiar. It's a shame that most people don't know what that is. It's literally basic high school science.

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Also I just went to Sea world and most of their deep tanks use MH as the primary lighting. The aquarium exhibit at the Manta coaster is amazing

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Not being "smart" in this technology means take with a grain of salt --
I have seen a tank lit by LED'S from 15 feet above here on RC by Timfish I believe.
He used 15 degree optics. Would this approach of running a narrow beam do the job?
 
Not being "smart" in this technology means take with a grain of salt --
I have seen a tank lit by LED'S from 15 feet above here on RC by Timfish I believe.
He used 15 degree optics. Would this approach of running a narrow beam do the job?
I would think so since coral is not a concern, but I still like halides. I'm lucky to live near the gulf stream so our water is very clear and from my eye perception nothing beats a 10-20k MH for true representation.

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Here's a question for the OP, hood or no hood?

My new tank is the first larger tank I've run without a hood, and I'm shocked at how much lighting it gets from the ceiling fixtures in the room. With the tank lights off, and only the room lights on, I can see everything absolutely perfectly.

For viewing the fish only, maybe just something like a track lighting set from the local home improvement store, with 10k LED's on it could do the trick.

-Hans
 
That’s along way down, MH sure. But hot and expensive to run.
Chinese blackbox push hi pars and $150 bucks, so maybe.......(no corals)
Would need to be mounted low, say 6-8 inches off the water.

Visparspectra 165watt, see on Amazon...
 
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