My first attempt do build a diy led light for planted aquarium 120cm /60/45 total 300 liter
I search the net for info and more i read more got confused
I know i want to use cree leds. Cool /warm white, some red and blue also. And use a dimmer
Any guidance will be Welcome.
If you use the XML T6, You will need between 30-40. I prefer to run the LED at 50% of rated current as it will make them last longer. Heat produced is lesser and manageable. Please purchase a few more LED's than you need; eventually one or two may fail and if you have spares its faster to fix.
Use Cool white LED's
Also add about 10 - 20 full spectrum Plant grow LED chips instead of Blue's and Red's
Try using LED"s that are rated at the same current. This will simplify the build as you will be able to use the same LED driver.
What type of heat sink will you use?
This is a over simplification... If you want to cool LED's Passively the heat sink needs about 20 square inches of surface per watt of energy *used* by LED. This is the ideal case. You can get away with 6 square inches of open surface area per watt for LED's. If the surface area to dissipate heat is lesser than this you will need fans.
For example if the energy used by all your LED's is 100 watts you need a heat sink that has atleast 600 square inches of surface area. here the wattage depends upon the current supplied. You can run a 10W Led at 2W by supplying 600mA instead of 2900mA of current. So since the energy used is less you can use a smaller heat sink.
Use some good thermal grease/Paste when mounting the LED's.
This really is a complex topic. Hope this helps. If you have any specific queries, do ask.