RBTA odd observation with lights

Ok so I have had LED's over my tank for the past 4 months,my RBTA has not moved since he settled in after I added the LED's (Boost mu135 2 fixtures).
This past weekend I decided to put a 250w phoenix 14k brand new bulb in a fixture above my tank to add some more lighting. My RBTA move all the way to the other end of the tank 48x48x12 in one day and has positioned himself directly under the MH. Think the RBTA even knows MH is still king? Has anyone else tried this?

 

What is the PAR for the two? I would guess a 250 Phoenix puts out a heck of a lot more PAR....

 

don't have a par meter personally so im not positive,but both are 14" above the tank

 

I'm not surprised.

http://www.3reef.com/forums/led-aqu...ite-sold-led-lighting-129504.html#post1286974

 

This tank is 12"? So, 2" off the bottom would be 24" from the light?

Where is the BTA?

From the Boost LED website, the max PAR of their MU135 at 24" is only 125-150 PAR. Even if the BTA was up a bit, 20" from the boost mu, the max par listed is 200-225....

When I was running a Phoenix 250W watt Metal Halide, with a Lumenbright reflector, 16" from the surface, I was getting over 800 PAR at the surface and 8-10' below that almost 500.

That isn't even a remotely close comparison LOL.


Boost Mu at 20"




Boost Mu @24"

 

I think that's the point. Leds aren't up to par with MH yet. I'm sure someday they will be, but not just yet. JMO

 

yea that's the point I was trying t make. I love my boost units don't get me wrong just saying MH are still king at this point and time,as my RBTA is showing me. Cant get much better proof than that of natural instincts from an anenome.

 

How do you get that out of the PAR from one LED?

If you understand how we measure light, we measure it as micromoles/m2/sec

So, we have light, per area, per time. We can remove time, as we are measuring light, at a given point in time.

So, we have light over an area. Let's say we are measuring light at 24" from the light source.

If you have a 120 degree light cone, at 24", the area covered would be
TAN(120/2) * 24 * 2 = 83" sqr.

If you have a 60 degree light cone, the coverd area would be TAN(60/2) * 24 * 2 = 28" sq.

So, with a narrower light cone, your spreading the same amount of light over 1/3 of the area. Therefore, the average light intensity (ppfd) over that area will be 3 times as much. So, you will have 3x the PAR!

Really though, LEDs are slightly less efficient than halides, overall. Sanjay Joshi published an article in Coral a while back and claimed LEDs put out about 15-25% visible light output, versus 27% visible output for halides (visible light is PAR by the way....). LEDs such as CREE 3W would be more like 25%. Halides vary though, so, 2% is nothing. The key is how you distribute that light. That makes a much bigger difference. Also, it depends on the halide. Higher kelvin halides, for example, may be much less efficient, so, LEDs could have an advantage.

 

If me and my gf, stand on one side of the room and call my dog and the dog comes to me. Does that mean the dog likes me more?

Hint: what I didn't tell you is that I had some peanut butter treats in my pocket

 

That led isn't up to par with that 250 watt metal halide... I can find a less powerful metal halide real quick that is a proper comparison..

It's not apples to apples like that. A stronger LED fixture is needed for a fair comparison. A proper comparison of equal photon strength will quickly show that a photon is a photon depsite the originator of it... halide, t5, led... doesnt' matter.