metal halide... what color spectrum?

[glarior]

Bought a new light for my reef setup. The metal halide bulbs that are currently in it is 15000k should I change them or use them?

Also, cyano bacteria... what color spectrum do they like? I am currently dealing with that. I have been told my old light system bulbs may be one of the reasons I am still having a problem. To much light? The old light was just a 24" 250w metal halide (I think 10000k? not sure) with 2 ancetic PC bulbs. Which is one reason I bought a new light 48" 2x 250w metal halide and then 4x 65W Compact Fluorescent Bulb Actinic Blue. The old light was to small across my 75g and use to be on my 75g hex.

[Regric25]

it depends on what you are looking for. If you are looking for growth 10000K is a good bulb. Usually 15k is a decent balance of bluer/higher par than 10K. If groth is not a huger concern and you like the look of the actinic blue and color pop you should try 20k BULBS. Thats what I use on my set up 2 250w 20K bulbs. I get decent growth but not fast and the color pops. Its really blue though but I like it alot. If I were to change my color temp I would go with 15K next but im content with my 20Ks. Hope this helps. If you want to see what XM 20K 250w bulbs look like on a reef system before you go out and spend money on bulbs you might not like, you are welcome to drop by and check my tank out. LMK

BTW from what I understand Cyano bacteria does not grow with light it feeds on excess nutrients in your water system. It could be lack of flow, infrequest water changes, feeding too much. Do you run a fuge, skimmer, filter media?

[CoryDude]

I would replace the current bulbs just to play it safe. That way you know exactly when to replace them next year.

Color is really a matter of taste. But, I've used 6.5 up to 20K, and my preference are the phoenix 14K's. Just a tad more blue than white, without going too far into the 20K spectrum.

And yeah, you'll have cyano no matter what color bulb you go with. Hair algaes tend to prefer the lower kelvin (more yellow) spectrums, so anything above a 10K is usually a good choice for reef tanks.

[glarior]

Well, I learned something new today! Thanks for informing me. I am going to stick with the 15k that comes with the new light but I will replace the bulbs sooner then that last set.

Thanks everyone!

[tony]

im a huge 12k fan without supplementation

[ErikH]

google Light Spectrum Enterprises. They make inexpensive good bulbs.

[OrionN]

I would replace the current bulbs just to play it safe. That way you know exactly when to replace them next year.

It is not as if the tank will crash the day the bulb reach 1 year, 6 months or 18 months. :-)

[CoryDude]

It is not as if the tank will crash the day the bulb reach 1 year, 6 months or 18 months. :-)

Really? Good to know I don't have to worry about that.

No, the reasoning for changing the bulb is so that you know exactly how old the bulbs really are. I misunderstood the op and thought the 15K bulbs were from a used setup. I've pushed the life of mh bulbs to 24 months in the past, but after only 12 months, you can tell the bulb is aging.

[OrionN]

I never believe that lights are the cause for algae problems. IMO, it is the nutrient in the water/tank and lack of herbivores that are the cause for all algae problems.

[StevenSeas]

I never believe that lights are the cause for algae problems. IMO, it is the nutrient in the water/tank and lack of herbivores that are the cause for all algae problems.

Not to hijack this thread but I fullheartedly respectfully disagree. This is because as time goes on the spectrum shifts in a bulb we all know this. The reason for this shift is pretty much the same exact reason that our car/trucks tires lose pressure over time. That is the gas molecules are small and the gaps in the walls (be it glass for our bulbs, or rubber in our tires) is relatively large. When the gas is moving inside its bouncing off the walls, occasionally slipping through one of these gaps. When the gas is excited (either by running electricity through it, or friction, both causing it to heat up) makes the molecules move quicker making the chances much higher per second of the gas making it out the gaps.

With our bulbs the gases that give us better par and bluer coloration, tend to be smaller than the rest so they escape the easiest/soonest. this causes a spectral shift to more of the red spectrum and away from the peaks that photosynthesis ideally occurs at. The macro algae and the calcerous algae that we grow in our tanks are much more focused and specialized in these peak ranges and dont absorb much outside of these. Whereas the more simple bodied algae requires less precise lighting requirements due to the way that the cell itself is designed. This means that it is more able to process nutrients than the macro and calcerous algaes. If something is more able to process nutrients then it will grow faster and outcompete it due to its ablity to addapt to advers changing conditions. These nutrients are already in the system, just before the bulb starts to shift color spectrum the beneficial stuff is able to outcompete the "unwanted" algae.

The macro alage is designed to be highly efficient at processing nutrients in a particular environment, whereas the algaes that we think of as being nucience algaes arent as fast at processing it but are more capable to change with the environment.

The lack of herbivores has nothing to do with it as they all have varied diets, and in order to keep them around to prevent a bloom they must be eating in that specilized diet, which means the nucience algae is present in your system already and is competing atlaest with the beneficial algae. And the amount that is being produced only allows for a certain amount of these herbivores to live, this is called a carrying capacity. That means it already has a foothold and thats all that it needs so that once something unfavorable happens the the desired algae the unwanted stuff can just take off faster than the amount of herbivores can handle it. So what most people do is add more herbivores, these control the unwanted algae and get it back to where it once was, now the carrying capacity has dropped so no longer may that many live. Thus you cant sustain enough herbivores in a tank to prevent an outbreak of algae due to other circumstances.

sorry for the rant, nothing personal just have had similar things come up before and wanted to get my opinion out there

[Big_Pun]

but I've seen a couple tanks and even mine that have had algae outbreaks after upgrading lights, when went from cf to t5 on my 29g biocube i had a red slime outbreak and the same with my pico when i went to LEDs. I may have had a nutrient prob but with old lights the tank was ok and able to handle it, but for some reason after each upgrade i got what seemed to be a recycle. just had to cut back feedings and add a phosphate remover water changes and just wait it out

dang you beat me aggie

[StevenSeas]

thats due to a sudden change in spectrum/intensity of light that the other algaes couldnt adapt to quick enough giving the cyano and others a step ahead and they took it for all that it was worth. jmo

[Roo&Lis]

google Light Spectrum Enterprises. They make inexpensive good bulbs.

Just bought a bulb from this company a while back. I must say I'm pretty impressed.

[ballardjr2000]

Just bought a bulb from this company a while back. I must say I'm pretty impressed. what Kelvin did you buy i am looking to order two 150w today. did you have to go up in rating or not i like the 14k look but if i need to get a 20k for the same as a phoniex 14k then i can do that too

[ErikH]

Ballard, go with a 20k. The 15k looks uber white.

[ballardjr2000]

thanks erik gonna order today also is the normal 20k good or should i go with the 20 "reef" i don't see what the differance would be with the light

[ballardjr2000]

ordered the 20k's they are "reef" type just had to look in the details. and yeah can't beat that price shipped 52 bucks for both pics to come later

[txav8r]

You will like them. I'm switching back to 20K soon.

[OrionN]

but I've seen a couple tanks and even mine that have had algae outbreaks after upgrading lights, when went from cf to t5 on my 29g biocube i had a red slime outbreak and the same with my pico when i went to LEDs. I may have had a nutrient prob but with old lights the tank was ok and able to handle it, but for some reason after each upgrade i got what seemed to be a recycle. just had to cut back feedings and add a phosphate remover water changes and just wait it out

dang you beat me aggie
The more light the more algae growth. With more nutrients certain algae grow faster than other. That is why nutrient is the problem. We put a ton of light in our tank and got lots of algae (both “good” and “bad”), anemone and coral grow. To control algae, we put tons of snails into it to eat the non calcareous algae. These snails can't touch the coralline algae so we have plenty of purple cover on the rock (if Ca is high in the tank)
That is the reason why I said algae problem is nutrient and lack of herbivores.

BTW, I never said anything about light not degrade interm of light output as the bulb age. This however is not the cause of algae problem in our tank.

[StevenSeas]

The more light the more algae growth.

Correct in general provided that the light is in the photosynthetic usable range (ie: PUR, something more important than but that gets overlooked for PAR)

With more nutrients certain algae grow faster than other.

True again, to an extent. However there are a lot of other factors to consider such as temp, ph, salinity, but in our stable systems the most important is the quality of light in the peak regions of the visible light scale that correspond to photosynthesis growth. Some algae are more able to adapt to a wider wavelength range of light than others, these tend to be the more simple algaes such as green hair, bryposis, and cyano. (I realize this isnt a true algae) while more complex, ie macro algaes, such as cheato. and caleurpa, dragons breath and others are more specialized and require a higher quality light, one that is closer to the peak regions of photosynthesis.

That is why nutrient is the problem. We put a ton of light in our tank and got lots of algae (both “good” and “bad”), anemone and coral grow. To control algae, we put tons of snails into it to eat the non calcareous algae. These snails can't touch the coralline algae so we have plenty of purple cover on the rock (if Ca is high in the tank)
That is the reason why I said algae problem is nutrient and lack of herbivores.

Thats not why nutrients is the problem, yes its the food, but one of the excess nutrients "predators" if you will, has been removed from the situation so you get an outbreak in population of the other "predators," the "bad" algae.

BTW, I never said anything about light not degrade interm of light output as the bulb age.

at least we can agree on something

This however is not the cause of algae problem in our tank.



I will get links later

[OrionN]

The crux of your argument is that MH bulb shift in spectrum as the bulb age and the shift cause the light output to favor less desirable algae and cause problem. This is fundamentally wrong.
The emitted spectrum of various metal vapors are fixed. It is the characteristic of a metal due to the configuration of it's electrons distribution. You can easily look up the spectrum of various metal on the internet. When I was in school umpteen years ago we had lots of fun in our physic labs ID various metals by analyze theirs spectrum. It have to do with quantum mechanic. As the electron absorb energy ti get boosted to a higher energy orbital state. When it fall back to a lower state it emit the energy in eletro-magnetic waves (photon). As the bulb age, some of the metal vapor get embedded into the glass (discoloration of the glass in old bulbs) incorporated into the electrodes and thus there is a net loss in the metal that produce light thus less light output. The spectrum of the light bulb remain the same but intensity decreased.
You can easily find information on Metal Halide light on the internet.


Thats not why nutrients is the problem, yes its the food, but one of the excess nutrients "predators" if you will, has been removed from the situation so you get an outbreak in population of the other "predators," the "bad" algae.
???I am not quite sure of your mean here???


In our tanks, everything grow as fast as it rate limiting needed allow it to grow. In a normal reef tank, the rate limiting need is not light but the essential nutrient that various organism (algae or otherwise) needed. That is why we have algae bloom in a new tank and the tank progress from one type of algae to another until most of the essential nutrient get "lock-up" in the biomass. There is no way we can keep a reef tank without herbivores. Even in nature, when the population of herbivores died like the urchins crashed in Florida in the late 80"s. The reef will be overtake by algae in short order. You can read about this if you want to do a search on the internet.

Sorry about the sidetrack of this thread

[StevenSeas]

From Bob Fernner on WWM
http://www.wetwebmedia.com/plantedtkssubwebindex/lightingags.htm

A note here on Spectral Shift. As they are used, all the differing light technologies change to known degrees in the percentages of what wavelengths they produce. Their luminosity decreases also, along with the preponderance of the desired spectral bands

You are correct that metals along with other gasses all have a signature light pattern that they put out. 100% undeniably this is true. However what isnt taken into account in your arguement, is a point that i made in the first post, "That as a bulb ages, different gases and metals leave the bulbs at different rates." This is a well known fact. That is what causes the shift, is the ratio of different metals and gases in the bulb changes, as some escape faster than others.
It is this spectral shift that favors "undesirable" algae.
Also I am not debating the fact about a new tank getting algae blooms, this debate pertains to spectral shift, which occurs to a detrimental point after about a year or more.

To OP, sorry about the shift of this topic, but I hope you can find the information useful for the future when it is time to change your bulbs. Also I hope that you are happy with what you ordered, please post pics so people in the future can use your experience for help in their own bulb selection.

[OrionN]

I would not trust this paper by Bob Fernner. He is clearly out of date in this paper. All you have to do is read what he said about MH in it.
Rather than this I would direct you to the many papers by Dr. Sanjay Joshi that can be found in the link below. Sanjay is an avid reefer and an Doctor of Engineering and a professor at Penn State. He extensively tested and wrote about MH lighting. Any serious aquarist who use or contemplate using MH light should spend sometime and read these articles.
Essentially according to these test, MH output decrease with time at all wavelenght. None of the wavelenght increase in intensity. Higher frequency wavelenght tend to decrease a little faster. At worst bulb, the intensity of light decrease by about 30% at two years. Anyway, I encourage the OP and anybody who follow this thread to read these series of articles, original publish by Aquarium Frontier and Advance Aquarist.
The major limitation of these studies is that he use different bulbs of the same brand at various age, not the same bulb at various age. Apparently there is significant variation from bulb to bulb of the same brand. Reading these articles help me a lot in determine which bulb to use and how often to change them. Read them and draw your own conclusion. Happy reading.

Here is the link:
http://www.personal.psu.edu/sbj4/aquarium/articles/

[ErikH]

http://www.manhattanreefs.com/lighting