from pl to led what to do?

[varke]

I run a single lighted screen of 50 cm wide and 8 cm down it is lit by a 55 watt pl 2700k lamp for 18 hours.
Now I order 20 X 3 watt 660 nm leds they run on 3.15 volt with max 0.9 amp I want to burn them at 0.450 amp to make sure the run good for a longer time.
I know two sides light is the best but than I make 10 leds on one side by one side 20 leds.
Must i chance the size of my scrubber ?
It is overflow fed and I use an Eheim 5000 liter pump.

Sorry for my bad englisch.

Greetings
Eric Jan

[Devs]

What do you feed, and how much per day ? This will determine the size of your screen. :)

[varke]

Sorry!
I made it for 4 bloks a day my system is 1100 liters.

[SantaMonica]

A 64 square inch screen only needs 32 watts of LED at the most. So you only need half of your LEDs.

[varke]

I will burn them on half power so 20 leds will consume 30 watts doesnt it work like that.
and i wil let them on for 9 hours.

[Floyd R Turbo]

http://algaescrubber.net/forums/showthread.php?1711-DIY-LED-Scrubber-Lighting-Guidelines-and-Builds Post 101 is the current recommendation

20" x 3" (50cm x 8cm, roughly) is 60 sq in

For 3W LEDs, you want one 3W 660nm Deep Red running at 700mA on each side of every 8 sq in section (minimum) or 4 sq in section (maximum).

For your screen, this means 60/8 = 8 LEDs per side or 16 total minimum, or 60/4 = 15 per side or 30 LEDs total maximum.

So if you have 20 total LEDS, 10 per side, but they are running at 450nm instead of 700, you are probably going to be close to the minimum. Should be OK as is.

[Floyd R Turbo]

forward voltage drop is not necessarily linear with current with LEDs. The efficiency (in terms of radiometric flux output per watt of power consumed) actually goes up when you dim LEDs. So if you have a rating that says "output is X at 700mA" and you run them at 450mA, 450/700 = 64% current (not sure what the voltage drop would be, but overall wattage would probably be proportional) but you may still get 75% of the output (flux) out of them.

[varke]

Thanx.
I must order the driver so a 0.7 amp must be better to use.
good to know I am on the good way.
This is still oke for feeding 4 bloks a day?

[Floyd R Turbo]

yes, it should be good for 4 cubes/day