How many LEDS to light a 150g

If you were talking CREEs, I'd recommend 72 to 90 MAX. 72x2=144 which is WAY TOO MUCH (at least if they were CREEs). I don't know much about Bridgelux, TBH.

Again, if they CREEs, 90 w/ 60deg optics would be fine. I'm using 60deg optics on a 24" deep tank and have SPS near the bottom, gaining in color and growth...

 

Should be okay, usually 60deg gives good PAR to around 18", but will depend on water clarity, spectrum etc..

 

so i should get 80degree optics with 90 leds

 

The lower the number, the better the penetration. I think 80 degree is only recommended to about 12". If you want to keep SPS to around 20", then 60 degree should be okay. If you wanted to go deeper, you'd probably want 40 degree.

Usually the recommendation is 80 degree for 0-12", 60 degree 12"-18", 40 degree 18"+. However, with clear water, you can probably squeeze a few more inches out.

Also remember you don't have a sand bed, so you are using the total depth of the tank.

 

How high up do you recommend to hang them?
Are you going to cover the tank with a glass cover???

 

How deep is your sand bed though? 3"? If around 3, for example, that would be 21" so near the bottom would probably be the 18-20" range....
No?

 

Correct on the deg/depth guidelines.

Yessir, correct again.

Was only stating what I said as a guideline for him to go off of, but the lack of sand bed for him is a very valid point that I didn't consider.

40 deg optics might be best for him, but he will need more diodes in order to get the spread in this case. So if the financial means are there, that's probably the way to go.

 

ok so my tank is 28"

and i need 40 degree optix with 90 leds correct??

 

tank has no glass cover... the leds will be 10" above the water..

 

Are you not worried about them getting corroded, or wet accidently?
What are the dimensions of the heat sinks?