Question on lighting for Coral growth

[Vaesive]

I have a 30w Cree LED setup for my Fluval Edge Nano reef with a light controller to emulate day and night cycles. I keep hearing that coral need 8 hours of daylight a day. Does this mean 8 hours at peak daylight or does that include sunrise to sunset?

Also, what percentages should I be running the lights at? The designer of the LED hood said not to push the LED's above 80% as it could damage the unit. At peak times I have the blues at 70% and the whites at 35%

My current lighting schedule is as follows (the color time changes are not immediate, rather, they slowly fade to the next setting over the course of the time period):

<table><thead><tr><th style="width: 80px" align="left">Time</th><th style="width: 80px" align="left">Blues</th><th style="width: 80px" align="left">Whites</th></tr></thead><tbody><tr><td>0:00</td><td>3%</td><td>0%</td></tr><tr><td>03:00</td><td>3%</td><td>0%</td></tr><tr><td>06:00</td><td>10%</td><td>0%</td></tr><tr><td>12:00</td><td>70%</td><td>35%</td></tr><tr><td>16:00</td><td>70%</td><td>35%</td></tr><tr><td>19:00</td><td>10%</td><td>0%</td></tr><tr><td>21:00</td><td>3%</td><td>0%</td></tr><tr><td>23:00</td><td>0%</td><td>0%</td></tr></tbody></table>
Essentially, the current setup has 4 hours of 'full light'

Any help would be greatly appreciated

 

[Vaesive]

Also, I should mention, I have LPS and just recently got some SPS.

 

[ReefWreak]

Corals don't need 8 hours of light. You can put a crappy light over them for 24 hours a day, and they will brown out and eventually die. Or you can light them with a 400w iwasaki for 4 hours a day and they will be bright and vibrant. They need enough light to live and thrive, to derive their energy and build their skeletons. Good quality light can deliver that in shorter periods, bad quality of light will never deliver that.

Unfortunately percentages that the lights at also don't mean much either, as if the lights are set in their hardware to be at 100% output as the max, then 100% will be 100%. On half of my lights, they are set that 100% is 100%, and the other half of my lights 100% is 50%, because of the way that some LEDs can only be run at 50%. Your LEDs may be ones that should only be run to 80%, and he didn't limit it in your LED drivers, so you can technically "overdrive" your LEDs, which will cut efficiency and could over heat them and burn them out.

If I were you, I would probably dial down your maximum light intensity to 40-50%, unless you have had corals at those higher numbers for a long period of time. Then I would set up your programming to a schedule that works for you. If you like blues, then leave whites off and only run blues. If you like a mix, then set up your lighting schedule for a "sunrise - daylight - sunset" schedule. My schedule has 30 minutes of ramping up blue in the AM and 30 minutes of ramping down blue in the PM, and then white kicks on and ramps up after or before those 30 minutes. Both whites and blues are at their fullest intensity (50%) by an hour after I have them come on, and are off again an hour after the ramp down starts. I have my lights run something like 10 or 11 hours I think. My corals color up nicely and have been happy, and my fishes have plenty of time throughout that timeframe to do whatever it is that fishes like to do all day.

But it's a matter of personal preference. In your situation, I probably wouldn't run your lights at below 35% intensity for less than 4 hours a day. Anything more than 4 hours a day in any combination that is more power than 35%, I think you should be fine. The rest is up to you.

 

[Vaesive]

Thank you for the response!

I've had my older coral using that lighting setup for months now and they're ok with it. I just would have expected to see some growth from them by now. My water params are fine for what I can currently test (Ammonia, pH, 'Trite, 'Trate, Phos, Salinity, Ca, kH). I just ordered a Mag test to see if that is ok. I do a weekly water change of 1g using Instant Ocean salt. I would think the coral are missing something since they haven't exhibited any growth but they are all open and colorful ('cept for the new one I just added; they're getting acclimated still). Only think left that I could think of would be that they aren't getting enough light. Could I be overlooking something?

Edit: Misspoke. My Zoas are doing fantastic and I have noticed growth from them. My Duncan and Hammer haven't really done anything in terms of growth.

 

[ReefWreak]

Generally a good way to tell if you have too little light (or too much nutrients) is corals turning brown. Corals turning light colored (even light brown/tan) or being pale can be too little nutrients or too much light. I generally use that as a guide for light.

If you aren't getting any growth, if they are LPS, you should probably try slowly directly feeding the corals more nutritious foods, and if they are SPS that are not growing, try dosing two part (though DO NOT DOSE ANYTHING YOU ARE NOT TESTING FOR).

 

[sittnon18s]

Pics?

 

[Vaesive]

Generally a good way to tell if you have too little light (or too much nutrients) is corals turning brown. Corals turning light colored (even light brown/tan) or being pale can be too little nutrients or too much light. I generally use that as a guide for light.

If you aren't getting any growth, if they are LPS, you should probably try slowly directly feeding the corals more nutritious foods, and if they are SPS that are not growing, try dosing two part (though DO NOT DOSE ANYTHING YOU ARE NOT TESTING FOR).

Thank you all for your assistance so far!

So the hammer has a brown body and, by what you've said, he could be needing more light. Strange since he's been there for months and has loved it there until now... I target feed the LPS corals frozen mysis shrimp and the SPS Reef Roids and Reef Chili.

By 2 part, do you mean this kind of stuff? I use that pretty regularly and with good results (although, being new to the hobby, 'good results' could be a misnomer).

 

[ReefWreak]

Thank you all for your assistance so far!

My pleasure

So the hammer has a brown body and, by what you've said, he could be needing more light. Strange since he's been there for months and has loved it there until now... I target feed the LPS corals frozen mysis shrimp and the SPS Reef Roids and Reef Chili.

Has he always been colorful until now? If that is the case, and lights have always been the same, then I would look at nutrients increasing or general tank stability issues.

By 2 part, do you mean this kind of stuff? I use that pretty regularly and with good results (although, being new to the hobby, 'good results' could be a misnomer).

Yes. 2 part is great for your tank, and promotes growth, but if you don't know what your levels are (you're not testing alkalinity and calcium), then that could be a parameter that you're spiking without knowing it, which could cause browning. I would recommend not dosing those at all until you start testing for them. Without much coral in the tank, without much growth on that coral, and if you are doing somewhat regular water changes, it is most likely that you're wasting your time and money by dosing 2 part, since you're replenishing minerals that aren't being used to begin with (or at a rate that necessitates you adding more of it).

 

[Vaesive]

My pleasure



Has he always been colorful until now? If that is the case, and lights have always been the same, then I would look at nutrients increasing or general tank stability issues.



Yes. 2 part is great for your tank, and promotes growth, but if you don't know what your levels are (you're not testing alkalinity and calcium), then that could be a parameter that you're spiking without knowing it, which could cause browning. I would recommend not dosing those at all until you start testing for them. Without much coral in the tank, without much growth on that coral, and if you are doing somewhat regular water changes, it is most likely that you're wasting your time and money by dosing 2 part, since you're replenishing minerals that aren't being used to begin with (or at a rate that necessitates you adding more of it).

The hammer had a white-ish tan body for a very long time with long extended, beautiful polyps. Now his body is brown but his polyps are the same color. They are a little more retracted than usual, though.

I test alk and cal pretty regularly and they are pretty stable. Ca was a little low a couple times but in general is around 380. I just double checked the levels for Alk and Ca requirements and it seems I could be upping my Ca levels a lil more. I'm beginning to wonder if the tank is beginning to stabilize again. I just moved office buildings a few weeks ago and noticed a significant drop in algae growth and beneficial 'pods decline but they seem to be coming back.

I could be overthinking what 'growth' actually means as well. Looking back at old photos I can see that the Duncan and other coral has shown definite grown in polyp extension and size but there hasn't been any new buds forming or anything.

I love this hobby. So much learning to be had and discovery