Getting my lighting correct

[fixedpoint]

I have had trouble keeping SPS in my tank in the past and so I'm running through each environmental parameter and checking it. I plan currently keep LPS, soft coral, zooanthids, and SPS. One thing that is hard for me to evaluate is whether I have set my lighting properly. How do you know how much lighting to use?

My tank is 30" x 15" x 15". My lights are 12" above the tank. I have a Radion xr30w Pro which is set to 30% of maximum (I just finished a blackout) following the "Radiant Colors" program.

When I first started the tank, I rented a PAR meter and recorded the value at various spots throughout the tank. Here is what I found when the lights were set at 50% of maximum.

<img src="https://dl.dropboxusercontent.com/u/38664265/tank-par.png" />

[thegrun]

Those numbers are okay, perhaps a little low for SPS, but then again they are slightly high for some softies. I would probably take it up another 5-10% and keep the softies that can't handle the higher intensities on the sides down low.

[whosurcaddie]

I would shoot for 300 par in the areas you want to keep SPS.

[DingDong128]

I have no idea if it's true or not, but I have heard many times that par numbers are not truly accurate for led lights. The logic is that the LEDs are putting out light not measured by par. I had a radion, switched back to t5, and found they could bleach corals quite quickly. I never did par reading on mine though.

[Cfabia1]

I used to bleach sps every time because I didn't light acclimate. Either start with them at the bottom and move it up over a couple weeks until you find what it likes best or turn the power down and slowly ramp up over the same time period. Works for me

[mushumatt]

I have no idea if it's true or not, but I have heard many times that par numbers are not truly accurate for led lights. The logic is that the LEDs are putting out light not measured by par. I had a radion, switched back to t5, and found they could bleach corals quite quickly. I never did par reading on mine though.

i believe that the whole led par thing is false but check this out http://www.illumitex.com/photosynthetically-active-radiation/

[Ron Reefman]

i believe that the whole led par thing is false but check this out http://www.illumitex.com/photosynthetically-active-radiation/

The whole led par thing is false???

What the heck does that mean? I read the article you linked, I'm not sure I understand how that applies to your comment at all? Care to elaborate?

DingDong, if you go to the Apogee website it will show you just were (what spectrum) the PAR meter is accurate and where it's weak. It's not a perfect tool, but it beats the heack out of just guessing.

[SoloGarth]

I have read that par meters are inaccurate due to an inability to compensate for the strong blue spectrum present in LEDs. I don't know if that is true and don't think a PAR meter is necessary. Just start very low. 30% is probably a good starting point. With my radion gen 2s I started at 45%. I have increased it 1% per week and am currently running at 82%. No bleaching. Just watch your corals. Flow and available nutrients affect the amount of light that can cause bleaching as well. This makes par measurements even less useful.

Another important consideration is photoperiod. I run a 6 hour photoperiod with the lights set to run dim blues/red for viewing purposes only for 3 hours on either side of the 6hr strong lighting period. This has worked well for me.

[SoloGarth]

Double post

[Shawn O]

DingDong, if you go to the Apogee website it will show you just were (what spectrum) the PAR meter is accurate and where it's weak. It's not a perfect tool, but it beats the heck out of just guessing.

WWW.APOGEE.COM seems to be an electronics technology adapted to music:
Apogee Electronics is an award-winning manufacturer of USB, Thunderbolt and Pro Tools audio interfaces for recording music on iPad, iPhone and Mac.


Anyway, is it that the blue wavelengths (400-500nm) have the same PAR output as white but just can't be read accurately by PAR meters? If so, couldn't one just take the par readings for their whites, adjust the whites to half of the desired end value and then adjust the blues to the same % value as the whites?

[Sk8r]

One problem is the depth of your rocks. If you could build those stacks just a little higher---SPS tends to come in very small frags, and I kept mine (I'm lps now) about 8" below a 250 watt 10000k Ushio (has more reds than some) Metal Halide. Yours look to be much farther from the light. I know you need that height for spread, but I'd build that rockwork high in the middle and concentrate the colored sticks on the upper tier, then put some montipora toward the outside of the cone---more tolerant. You can see how very fast the numbers fall away as you get deeper.

[nuxx]

Agreed, I'd say bump it up another 5-15% and you should be good to go.

[mrbigshot]

For some acros 800+ par is acceptable. As others have mentioned 200 is low. LPS will do good in 200-300. Most sps want 300 as a minimum. The more light the more flow.

[fixedpoint]

This has been super helpful. Thank you everyone for your input. I'm definitely going to make some changes.

One follow up question ... So far the conversation has focused on using the PAR readings to get the right lighting. What can I observe in a tank that will help understand if I have too much or too little light? What are the symptoms. For example does bleaching happen with too much or too little light? Does it happen faster in low light than in high light?