LED Height

Well I finally got around to finishing my DIY LEDs. There are 108 3W Cree LED's (72 RB/BL and 36 CW/NW) mounted about 13 inches above the waterline. My tank is a 180g 72x24x24 SPS tank. They are replacing 2 400w MHs and in terms of brightness (at least to the human eye) it looks pretty comparable. I realize there are intensity differences between LEDs and MHs so I just want to make sure I get these mounted at an appropriate height. 


Here's how it looks from the front:



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And from the back:



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Any advice would be appreciated, thanks!

 

Figured I should probably add that the blues are driven at 850mA and the whites are at 1.3A. The blues are currently dimmed at about 90% since I thought things looked too blue for my liking at 100%.

 

I've never used a PAR meter before. Anyone in the IC/CR area have one they would be willing to lend? What kind of values should I be targetting near the top and bottom of an SPS tank?

 

That would be awesome. I've been meaning to make it up to the store at some point since I moved out this direction since I've heard nothing but great things. What kind of hours do you have?

 

Thanks! I suppose I should probably also get an address as well. I think I'll try to come in next week to pick it up if that works for you. I'll just turn my LEDs down quite a ways to play it safe in the meantime.

 

Thanks. Now I'm thinking I should probably get an apex controller hooked up so I can play with the settings to get a better understanding of the relationship between PAR outuput and dim settings. I probably don't want to just turn my analog dimmers down to an appropriate PAR level and call it good since I won't be able to know what dim % I'm at. I'll get an apex jr and vdm module ordered pretty soon here and hopefully I'll be able to get the PAR meter from you next week.

 

I finally managed to pick up the PAR meter yesterday and played around with different light settings to dial in to an appropriate PAR. My one concern is I've heard that blue LEDs have their PAR underestimated with PAR meters.

I have a 2:1 B:W balance with my LEDs with blue at 70% and white at 60% and I'm reading about 200 at the sandbed and around 500 at the top of the rockwork. Am I going to end up scorching everything or is the error on the PAR meter somewhat trivial?

By the way Craig I was extremely impressed with the store... that was the first time I've made it over there. I'm also impressed that I was able to contain myself to picking up only 3 frags!