Can LEDs shift in spectrum?

Bongo Shrimp · Sep 16, 2013

I bought a custom LED fixture from nanotuners back when they were in business probably 4ish years ago. It has 15 white Cree XR-E stars and 15 blue. They were underpowered for a while because the drivers were not calibrated when it was assembled. Then evil66 helped me get them calibrated and they were much more powerful, sustaining SPS very very well. The success lasted for approximately a year, running the LEDs at 100% power using the ALC module with a Reefkeeper Elite and then things went haywire. I have been having trouble keeping almost any corals, especially SPS. My one mushroom is bleached, my zoas are somewhat bleached, and my darth maul porites which should be deep red, is pink. I also noticed that most if not all of my coraline algae has died or become extremely pale. I have tested the water over and over, checked for stray current and even heavy metals. My fish are fine and my numerous acro crabs and one pistol shrimp are alive and well along with my snails and two year old halloween hermit crab. I had given up.

Then today I noticed something. I noticed that the coraline that is slightly shadowed, aka not getting direct light, is pretty deep purple and seemingly healthy. It is very easy to see on the rear top corners of my tank and in some slightly shadowed areas on the rocks. Also, my porites is light pink on top but more red on the sides where it has grown down vertically on the rock I bought it on. So now I am convinced it has to be my lights. One friend of mine suggested the LEDs shifted in spectrum. I didn't think this was possible, nor does it make sense that some coraline would be healthy and the rest not because it only get less light, not a different spectrum (correct me if I'm wrong). Could I be running the LEDs too high? This is not a stability issue because I run a dosing pump which keeps my levels rock solid by dosing alk and cal 16 times a day. Mag is stable from water changes although I test it and adjust if necessary.

A few other weird symptoms include the SPS STNing slowly from the base for a few weeks, then going faster and faster, and eventually either stopping and getting better or just dying completely. Also I have been battling bryopsis which goes through a similar cycle of slowly dying off further and further and then coming back in force.

I hope this isn't too confusing, just trying to be thorough. LMK if anything needs clarification. I'm really at wits end and appreciate any input.

Tank stats:

Biocube 29g
15 White Cree XR-E LEDs and 15 Deep Blue @ 100% power via ALC with Reefkeeper Elite
Mediabasket in second chamber for filtration with polyfilter, carbon filter pad, chemipure and rowaphos
DIY Fuge with chaeto
2 Vortech mp10s

Temp- 78.5ÂºF
Salinity- 1.025
pH- 8.1 (API)
Alk- 9.8 (salifert)
Cal- 450 (salifert)
Mag- 1450 (salifert)
Phos- 0.03 (salifert)
Ammonia- 0 (API)
Nitrate- 0 (API)
Nitrite- 0 (API)

Tank inhabitants-
Pair of A. ocellaris
Pistol shrimp
A few hermits, a trochus snail and a few nerites
A few SPS, zoas, a mushroom and porites. All unhappy.

This is an example of what the LEDs were capable of several months ago:

I can get a picture of the difference in coraline coloration if anyone needs to see.

CoryC · Sep 16, 2013

LEDs dont last forever. 4 years is about a 1/4 of their life, however they could be overdriven since they were likely more primitive LEDs not necessarily capable of being driven near their full potential for extended time and that has caused them to give off inadequate spectrums? just throwing stuff out there.

cparka23 · Sep 16, 2013

LEDs definitely shift in intensity over time. You can see this for yourself in Cree application notes. They say that the LEDs are expected to retain 70% of their intensity when driven for 50,000 hours at some given current. Of course, you'll get a different "lifetime" depending on the temperatures, humidity, etc. 4 years of use isn't substantial as long as the LEDs were driven and cooled reasonably.

As for shifts in spectrum, this doesn't occur unless you say one color becomes less intense than another. However, the output from a blue LED does not shift towards royal blue or green. You only get attenuation of wavelengths already present in the output.

Not sure what to say about your SPS, though. Kind of surprising that you'd see bleaching in shrooms and zoas, too.

ReefLEDLights · Sep 16, 2013

Older 1 watt LEDs may shift spectrum when dimming with PWM. The Cree you have should keep their spectrum.

How is the temperature on the heatsink. If the LEDs run too hot they will not last and become dimmer over time. 3 and 5 watt Cree LEDs keep their spectrum very well over time.

Its not unheard of to have SPS grow like weeds then all of a sudden dont do as well. It might be something besides the lights as the Cree Cool white has a very nice 450nm spike which is great for growth.

Bill

Ron Reefman · Sep 17, 2013

You gave us lots of info to deal with in trying to help. The one thing that would be really wort having is a PAR reading from back in the past and what it is now. That doesn't look at spectrum shift, but I really don't think spectrum shift is that big an issue. And it would take a very big spectrum shift to cause the kinds of issues you are dealing with. Are these dimmable leds? Have you changed anything else?

Bongo Shrimp · Sep 21, 2013

Thanks everyone for the replies and sorry for being so slow to respond. I have dropped the whites to 50% and blues to 75%. So now I'm going to give it a week or two and see if anything changes. I originally thought it had to be the water too but I have tested and tested everything over and over with different kits and different brand kits and its all reading fine. I have not changed anything else because I had pretty much given up. I also found it puzzling that the zoas and mushrooms are having issues too.

Ron Reefman · Sep 22, 2013

A suggestion. With the equal number of white and blue leds in your fixture, I'd run the blues high enough to get near the PAR you want and then slowly dial up the power on the white leds. As soon as the overall look of the tank is as white as you want it, say 10K or 14K or 20K, then don't add any more white.

The blue spectrum is mostly for the coral's zooxanthellae health and growth and a little for our eyes. The white light and it is mostly for our eyes and only a very little bit for the good of the coral. White light has no spectrum as it is a mix of spectrum- mostly red, green and blue. The white leds add some red spectrum which zooxanthellae can use.. but most corals don't need much.

Adding more white does add PAR, but adding PAR by increasing the blue 2 or 3 times more than you increase the white and keeping the minimum amount of white will be better for the coral. I'll bet you end up with the blue at 3 or 4 times the power of the white, maybe even more. My fixtures are almost 3:1 blue to white and I run them at 90% blue and 40%-50% white in order to just get to a 12K-14K white overall look in the tank.

H@rry · Sep 22, 2013

Have you checked for stray voltage? Do you have a ground probe?

username · Sep 22, 2013

I have a similar thing happening with some of my sps. I run 3w cree that are driven and cooled properly. Tank has been growing like weeds for almost 2 yrs. just the last two weeks I have been noticing that some sps are stning from the base, others have partial rtn. I would have to attribute all this to two factors in my tank. We had a heat spell that lasted for 2 weeks or so, tank got to 83 a few times before i could get home to cool it down, a swing of 79.3 to 83 isnt good. Then i had a week where the temps were 81-82.5 constantly, are local temps are around 72 in the summer and we had temps of 80. The other factor was I had a house sitter for a week and she fed the fish in 3 days what i normally feed in 2 weeks, so i assume i had a spike in nutirents then causing some stress to corals and later a cyano and hair algea outbreak.

Sorry for the winded post, I do not feel your lighting is causing what you are experiencing. I would say something less obvious is causing it, and it may have been corrected without you knowing what went wrong. Remember sps dont react the same day something goes bad and can take weeks to react when conditions are improved.

ReefLEDLights · Sep 23, 2013

username said:
I have a similar thing happening with some of my sps. I run 3w cree that are driven and cooled properly. Tank has been growing like weeds for almost 2 yrs. just the last two weeks I have been noticing that some sps are stning from the base, others have partial rtn. I would have to attribute all this to two factors in my tank. We had a heat spell that lasted for 2 weeks or so, tank got to 83 a few times before i could get home to cool it down, a swing of 79.3 to 83 isnt good. Then i had a week where the temps were 81-82.5 constantly, are local temps are around 72 in the summer and we had temps of 80. The other factor was I had a house sitter for a week and she fed the fish in 3 days what i normally feed in 2 weeks, so i assume i had a spike in nutirents then causing some stress to corals and later a cyano and hair algea outbreak.

Sorry for the winded post, I do not feel your lighting is causing what you are experiencing. I would say something less obvious is causing it, and it may have been corrected without you knowing what went wrong. Remember sps dont react the same day something goes bad and can take weeks to react when conditions are improved.

In the past I've had similar problems with SPS. I upped my soft flow using Ecotech and Tunze Pumps...Huge difference...

You cant short the following:

Live Rock

Flow

Skimming

Lights