HELP with LED decisions

[alextheromanian]

LEDs...yup.
the current system is a 72 inch long 3x175W MH bulb...and it comes with a built in 30X 2 T8 actinic....since the T8 is only 30 inches and one is on one half of the fixture and the other is on the other HALf...on the OTHER SIDE of the MH too...lets just say colors dont pop as well as they could and daylight is more the name of the game this lighting fixture spits out than anything

heres a rough sketch of how its set up from the factory.




and heres are two possibilities of what could happen with it both having their pros and cons.

this one will take little to no modification. aside from adding two brackets on either side but will take up more room and leave the leds exposed to the saltwater enviroment.


this will require taking out the lighting...gutting out the T8 so theres work there but the pros would be ...LEDS are higer up(PRO?) and they are hidden behind glass and cooled by the lightings own built in cooling system




questions now are....


1)what do you guys think is better do do of the two options

2)How far apart should leds be...(just using royal blue) and how many for a 72 inch long fixture...dont want to overdo it.

3)what would be the correct ballast i should look at. preffer it to be dimmable and id prefer to have just one...if not possible then ill use 2 ( one for each side)


thanks for your help and i hope i wasnt too confusing.

[TheFishMan65]

I like B, add some lenses and the height will not be a problem. I would do eithe 12, 18, or 24 LEDs on each side just because it goes well with most drivers. Probably 12 a side evenly spaced.

Look into the HLG series of driver if you are thinking of doing more than 24 now or int the future. Otherwise use a ELN and run 2 parallel strings.

Realize that putting them near the MH will make them hot so make sure the fans work well.

[alextheromanian]

Originally Posted by TheFishMan65

I like B, add some lenses and the height will not be a problem. I would do eithe 12, 18, or 24 LEDs on each side just because it goes well with most drivers. Probably 12 a side evenly spaced.

Look into the HLG series of driver if you are thinking of doing more than 24 now or int the future. Otherwise use a ELN and run 2 parallel strings.

Realize that putting them near the MH will make them hot so make sure the fans work well.

the fixture has 120mm thick metal fans on each end. one pushes the other pulls and and the glass is warm to the touch ...not hot which assures me the heat isnt much of an issue...not to mention that the way the tank is built theres a draft from the AC right into the canopy and rest of the cabinet seeing as how this goes from floor all the way to ceiling and the room was built around it.

the less the better. all i need is to get colors to pop the way they should...and have seen many whith diy LED fixtures that put too many and bleached the tops of their rockwork needing to move the corals lower.

72 inches...with 12 per side...they would come out to be about 6 inches apart...isnt that too far ? perhaps 18 per side is more correct?

is this the power supply you were reffering to?

http://www.onlinecomponents.com/MEAN...tml?p=37809828

[TheFishMan65]

I guess I should pay more attention somewhere I was thinking 48 inch tank. That driver can do 24 LEDs in 2 strings of 12. It only cost about $35 so maybe 2 of those since an HLG is closer to $100. If you go 2 you could also go with 48 LEDs.

Just a thought on bleaching. Generally I consider 24 LEDs to be the same as a 250 watt MH halide bulb. It depends on current the LEDs are running at, optics, and some other considerations, then if they are all royal blues the spectrum is different. But what I am getting at is that you may still have acclimation issues.

[alextheromanian]

http://www.rapidled.com/servlet/Cart?cart_id=25844107

and these would be the LEDS....cheapest royal blues i found.

well acclimation id rather avoid...but what if i put 12 per side...and it looks like random interval spotlights....the only LED fixtures ive seen have leds packed about 1 inch apart...its why im concerned...and from the HW ive done 1W leds...dont do a decent enough job and drown in the daylight...

again this is JUST for actinic use to make colors pop properly so the tank doesnt look like it has sunlight for a lighting fixture.

[TheFishMan65]

Try 12 per side you can always add more if you decide you need more. How high up is the fixture? There all the same color so you won't need to worry about mixing colors of LEDs. If over 12-18 inches I would start considering optics even.

[alextheromanian]

Originally Posted by TheFishMan65

Try 12 per side you can always add more if you decide you need more. How high up is the fixture? There all the same color so you won't need to worry about mixing colors of LEDs. If over 12-18 inches I would start considering optics even.

i may be wrong but i do believe the tank is 18 high and the fixture hangs another 5-6 inches above that

do leds spread out light decently? i just dont want to do 12 per side then find out i have straight beams of light every 6 inches thats all.

[TheFishMan65]

Their angle of spread is 110 or 120 or maybe even 130. I don't think you will have a problem at 5-6 inches with no optics.

[alextheromanian]

cool ty. ill go for the 2x24 drivers...and 12 for each in that case...or perhaps ill ger only one side...if it looks ok with 12 on one side ill just get another set of 12 and skip the other driver....if needed more ill get more and a second driver and shoot for 18 per side.