Correct PAR to aim for?

[ssick92]

Hey everyone,

A local reefer is going to lend me his PAR meter today. What numbers should I be aiming for? I have heard some people say 200 at bottom of tank and 700 at top, and I have heard people say 350 at bottom and 1000 at top.

What do you guys think are the "proper" numbers for a mixed reef tank with SPS, LPS, softies, and hopefully a clam if I can find one for a reasonable price.

Thanks for your help.

 

[solitude127]

In my tank, the middle in the bottom is about 250 and the top is hi 600s. Off to the sides, the bottom was in the mid 100's and the top was in the hi 300s. I had mostly SPS. Most of my LPS were in shaded areas of the tank.

I really don't believe that there is a "correct" number, you just have to be observant and see how your corals react to placement. I had a SPS up hi and it was pretty good color but then I moved it down low and the color got better.

 

[Aqualund]

Here is a study reflecting optimum growth rates for coral vs par.

http://www.advancedaquarist.com/2013/2/aafeature

Most of all the corals for fluorescence and coloration have about the same values for par...but there are a few acropora that only fluoresce at like 700par...but that is deemed more detrimental than beneficial in the article.

so if you go by this study...between 150-300 is optimum.

 

[ssick92]

Well after using the PAR meter, I learned that my lights were too high. I had them at about 10" above the surface and I was only getting about 175 at the surface of the tank. I also learned that my tank doesn't have much of a difference from the surface to the bottom. I moved my lights down a bit and now the surface of the tank is at 450 and the bottom is at around 200.

 

[solitude127]

What kind of lights are you using?

 

[ssick92]

What kind of lights are you using?

I have a 5x39w T5 fixture.

 

[HurricaneSystem]

If the figures you gave are correct after moving your light, that is about perfect.

 

[ssick92]

If the figures you gave are correct after moving your light, that is about perfect.

Ya, I double checked this morning and those numbers are pretty spot on. Glad I was able to finally figure out my light output.

 

[HurricaneSystem]

Yea, a PAR meter takes most of the guessing out of programming the intensity of LED's. I understand you have T5's and those are fantastic as well. I think you should be good with most anything you want to keep.