PAR question: Lower the fixture?

[screebo]

I've found that I have a range from top of reef to bottom substrate between 200-350 PAR with all lights on. No scientific guessing please, if you've studied PAR values and general livestock requirements, please chime in with an answer to this question: Should I lower my light fixture to raise the PAR values of my tank?

Thanks!

 

[GreshamH]

I've found that I have a range from top of reef to bottom substrate between 200-350 PAR with all lights on. No scientific guessing please, if you've studied PAR values and general livestock requirements, please chime in with an answer to this question: Should I lower my light fixture to raise the PAR values of my tank?

Thanks!

You are missing a crucial piece of information... what the heck do you want to grow on you substrate? The amount of PAR you listed is good for even SPS... and you want more light

 

[screebo]

I've found that I have a range from top of reef to bottom substrate between 200-350 PAR with all lights on. No scientific guessing please, if you've studied PAR values and general livestock requirements, please chime in with an answer to this question: Should I lower my light fixture to raise the PAR values of my tank?

Thanks!

You are missing a crucial piece of information... what the heck do you want to grow on you substrate? The amount of PAR you listed is good for even SPS... and you want more light

Thanks, Gresh. It's WAY easier to leave it as is than lower it. I've got about 11" between the fixture glass and the top of the water. I somehow expected higher levels than that. It's funny that the PAR level does not change much between the bottom of the tank and the top. The acros and millis show nice new growth all around but I want to consider optimum settings. I may simply increase the photo period a bit and see how it goes. I'll watch how that may affect algae growth as I have a minimum now. Thanks for the quick reply.

 

[r0ck0]

I was wondering if like most devices it required calibration. According to this article it shouldn't. But it may report lower PAR because of the color of light. Is that correct?

In my opinion, objections to the validity of the Apogee's measurements based strictly on the issue of spectral response are unjustly founded. The largest source of error lies squarely (but potentially) with the user of the instrument, and not inherent optical qualities. User error includes sensor orientation, sensor cleanliness, instrument condition (care, maintenance, calibration) etc.

It would seem that any reports of PAR and PPFD measurements should include the instrument's last calibration date or at least a report of deviation from a standard light source or calibrated quantum meter.

http://www.advancedaquarist.com/2005/7/review#h10

 

[GreshamH]

I was wondering if like most devices it required calibration. According to this article it shouldn't. But it may report lower PAR because of the color of light. Is that correct?

In my opinion, objections to the validity of the Apogee's measurements based strictly on the issue of spectral response are unjustly founded. The largest source of error lies squarely (but potentially) with the user of the instrument, and not inherent optical qualities. User error includes sensor orientation, sensor cleanliness, instrument condition (care, maintenance, calibration) etc.

It would seem that any reports of PAR and PPFD measurements should include the instrument's last calibration date or at least a report of deviation from a standard light source or calibrated quantum meter.

http://www.advancedaquarist.com/2005/7/review#h10

There have been 3 models since then as well as a change in the sensor (article is 5 years old)

 

[GreshamH]

I've found that I have a range from top of reef to bottom substrate between 200-350 PAR with all lights on. No scientific guessing please, if you've studied PAR values and general livestock requirements, please chime in with an answer to this question: Should I lower my light fixture to raise the PAR values of my tank?

Thanks!

You are missing a crucial piece of information... what the heck do you want to grow on you substrate? The amount of PAR you listed is good for even SPS... and you want more light

Thanks, Gresh. It's WAY easier to leave it as is than lower it. I've got about 11" between the fixture glass and the top of the water. I somehow expected higher levels than that. It's funny that the PAR level does not change much between the bottom of the tank and the top. The acros and millis show nice new growth all around but I want to consider optimum settings. I may simply increase the photo period a bit and see how it goes. I'll watch how that may affect algae growth as I have a minimum now. Thanks for the quick reply.

Longer photo periods do not really help, the peak PAR is what is most crucial. Sounds like you need to read Jake Adams articles on light and water flow

 

[screebo]

I will read the articles. Thanks for the connection.