par meter test results

[james30ct]

I posted this in the general discussion but I figured I would post it here also to get as much feedback as possible.

So our local club has an apogee par meter that a borrowed to test my tank. I have a 155g bowfront with 3 reefbreeder value fixtures. tank is 24 inched deep.
I have the blues set at about 75% and the whites at about 65%

I am getting mid 300's at the top of the tank and 90-100 at the bottom. I have a squamosa on the bottom that does good and various sps throughout the tank.
Should I be concerned that the par is so low on the bottom? I know par is different with leds but not sure whats ideal. I also have a gig anemone on the bottom that also does ok.

I did the test with all powerheads off. Thanks for any input.

[Tweaked]

From what I understand as well, par meters have to be spefic for LEDs. The apogee site reccomends the MQ-200 for LED readings. I did find this info as well.

Apogee PAR Sensors Spectral Errors Under Electric Lights
All Quantum/PAR sensors on the market experience a certain level of error under different electric light sources. The following data can be used to adjust the PAR readings of Apogee Quantum sensors to achieve highly accurate readings. Please note that these errors apply only to quantum sensors that are pre-calibrated for electric lights, and for the Quantum Meter when it is set to "electric light" mode.



LED Type

Error [%] for Apogee Quantum Sensor
Cool White -4.2
Neutral White -6.1
Warm White -9.9
Blue (448 nm) -10.7
Green (524 nm) 5.8
Red (635 nm) 4.7
Red, Blue 2.7
Red, Green, Blue 3.5

Other Electric Lights

T5 Cool White Flourescent 0.0
T8 Cool White Flourescent -0.3
T12 Cool White Flourescent -1.2
Compact Flourescent -0.2
Metal Halide -3.9
High Pressure Sodium 0.8

[james30ct]

Thanks for the info. Thats probably hard to factor on a full spectrum unit. I'm planning to add 2 60" diy t5's to help but Im trying to find a way they wont look bad without a canopy.

[james30ct]

Ill post whatever responses I get from forums here so it might help others with leds also.

Heres one I got here on rc

If your corals are doing fine, then you are providing enough PUR (Photosynthetically Usable Radiation). PAR is useful for determining intensity of all visible wavelengths (400-700nm), but corals don't use/need all of these wavelenghts since zooxanthellae photosynthesis is driven by violet, blue and red (only shallower water corals receive red in nature). LEDs tend to be heavy in the bluer wavelengths, so that's why corals under lower PAR can still receive adequate PUR.

Heres one from another forum (not sure I'm allowed to say which one)

check out this article about PAR vs PUR http://www.americanaquariumproducts....ng.html#energy

the whole article is informative, but specifically #5

it talks about usable light radiation vs visible; and that (specifically with LEDs due to their exact colors) a low PAR rating doesnt necessarily mean poor coral growth, because the radiation they're receiving is within the desirable or usable range. There are a few reports of people growing SPS under 100PAR reliably

TL;DR is PAR doesnt mean for LEDs what it would for MH, VHO or T5; if your corals are showing good signs of color and growth under low PAR, its likely because their receiving adequate light

if youre concerned theyre not getting enough light, you could try increasing the intensity and decreasing the hours until they acclimate

[Tweaked]

Probably part of the "secret " to LEDs cause I've seen some amazing LED tanks, but for me it was a bust. Halides all the way for me, t5s for supp., and LEDs for pop. Just one idiots opinions

[james30ct]

One thing Ive seen with almost every led tank is the coral shading which I'm hoping the t5's will help with.

[Tweaked]

Sure will. What fixture or kit are you going with

[james30ct]

I bought 2 diy reflectors with ati bulbs off a member on here. I bought sockets and a workhorse ballast. Ive been trying to come up with ideas that wouldn't look bad. My first thought was to cut a channel in 2"pvc and put caps on the ends with computer fans in them and paint it black, then put the ballast inside one of the tubes and set the reflectors in the channel. Just not sure if it would get hot enough to cause the pvc to bend.

[PL-Reef]

You can go buy some aluminum C channel and mount the sockets and reflectors to that. if you're creative you can make it look really clean and simple.

[phillrodrigo]

I'm in the same boat with james.. I've been wanting to add t5 to my led but how to do it without looking like a fire hazard.

[PL-Reef]

What about looking for an old light fixture and gutting it and put you retro lights into it?

[triggreef]

I think you can go a little more one the lights. I'm up to 90% blue channels and about 60% white channels. Thats what it tops out at and my tank gets that blast for 5 hrs. Rapidly going down after the 5 hours and the ramp is opposite on the other side. I don't have it in front of me but I think I have it so it goes down by about a third in the first declining hour and about 1/2 of whats left in the second declining hr.

Be careful thought you really do need to take your time adding light. I never went by more than 10% at a time (over a 3 weeks period) and I started at around 40% and 20% max, maybe even less.

At my current rates I get about 120 to 130 par over the entire sandbed. Its about 160 par only about 5 or 6 inches higher, where I have milli's growing.

[james30ct]

Originally Posted by triggreef

I think you can go a little more one the lights. I'm up to 90% blue channels and about 60% white channels. Thats what it tops out at and my tank gets that blast for 5 hrs. Rapidly going down after the 5 hours and the ramp is opposite on the other side. I don't have it in front of me but I think I have it so it goes down by about a third in the first declining hour and about 1/2 of whats left in the second declining hr.

Be careful thought you really do need to take your time adding light. I never went by more than 10% at a time (over a 3 weeks period) and I started at around 40% and 20% max, maybe even less.

At my current rates I get about 120 to 130 par over the entire sandbed. Its about 160 par only about 5 or 6 inches higher, where I have milli's growing.

Thanks. I turned them up a little bit but I do it very slowly beacuse these fixtures dont ramp up and down. Its on or off.

[Chriskid]

Originally Posted by Tweaked

Probably part of the "secret " to LEDs cause I've seen some amazing LED tanks, but for me it was a bust. Halides all the way for me, t5s for supp., and LEDs for pop. Just one idiots opinions

2......lol