MH degradation

[JJG]

Couple question here:

What is the normal "real" life expectancy for Metal Halide bulbs and specifically the Iwasaki 250w run with the PFO Eye (MV) ballast?
What effect does the age of the bulb have on brightness and "K" shift?

My bulbs are over two years old and while working fine don't seem as bright as I think they should. Also, SPS frags that had nice color originally have browned out.

If I have to change out the bulbs I'm struggling with whether or not to change the ballast and go with a different system. It's only time and money right?
JJ

[Todd]

I have the exact bulb and a DIY mercury vapor ballast. My bulbs are over a year old now. The average recommended replacement age for most MH I've seen is about 6 months. The Iwasakis do last a lot longer. As I understand it they also run brighter on a Mercury Vapor ballast then they do on a real Metal Halide or electronic ballast. While I understand the Iwasakis do last longer I suspect that over two years is beyond their prime. I'm looking at replacing the two I have now.

These bulbs, as most, shift spectrum over their life. As I understand it they shift to a warmer spectrum. As well, when replacing the Iwasakis I think we should look for the "R" designated bulb. I believe the "R" stands for "reef" and puportedly starts out a bit cooler (I want to say 7100 K) or so starting temp.

The PAR value of the Iwasakis is very good, particularly when run on a mercury vapor ballast. The 6500K is just too yellow/orange for me. I'm looking at replacing the two Iwasakis I'm running with new ones and buying additional flourescents to supplement with additional bluer spectrum. I have two 96 watt power compacts now and I'm considering adding two T5s.

[TBRUZZ]

I've read and have been told that the iwasakis last for 18 monthst..

[JJG]

Tank was originaly set-up as a SPS/softy mix so used the dual 250w Iwaski 6500K (R) with the matched PFO Eye ballasts and two 110w VHO actinics to balance the yellow of the 6500K MH. The softies beat out the SPS and became a softy only tank.

Since the move and tank crash, the tank will now be SPS only. Debating on saving the money and replacing with the same Iwasaki 250s or the whole system. Possibly 400w Ushio 10000k. Hummmmmm??
JJ

[Graham]

John,

I have seen data suggesting that the Iwasakis will start to decrease after about a year on any given magnetic ballast. Since they are a full-spectrum bulb, you likely won't notice the spectral shift/change. Since they are putting out the same wattage regardless, your eye won't see an intensity decrease.

That your corals are turning brown means the zooxanthellae are multiplying and/or the photoprotective pigments are diminishing - all signs that it's time to change your lights! Nasty algae and cyano are also more prone to grow as spectrum degrades...

[civil]

These bulbs will last a long time, or at least they will produce light. The issue is intensity. Most single ended bulbs last in the 8-9 month range. Some of course are less and most will work longer. All bulbs start to lose intensity very quickly. We do not have any perception thus think things are fine. If all the corals, especially those that have been in the tank a long time start to change it is likely an indication that the bulbs need to be changed. To keep the best color change the bulbs on a regular schedule. Also when changing do not change both at the same time. The change in intensity may stress the corals. It is best to acclimate the tank to the new bulb by raising the hood up and possibly reducing the time then slowy increasing time and lowering the fixtre.

[David Grigor]

If you guys can remember when Bob hosted a meeting at his house. His 75g had on new 65K Iwasaki on the right and a 12 month old one on the left. While spetrum may not have a major shift there was an obvious loss of intensity.......

I conclude that 12 months is when I would change them out based on my experience. I have always used MV ballast.

[Graham]

Hmm...if the bulb is a 250W bulb, I would think it would still be putting out the same amount of energy - otherwise I'd think there would be harm to the ballast. As in, it's sending 250W to the bulb, but the bulb is not using all the wattage. Much like if you ran a 175W bulb (for example) on a 250W ballast?

Maybe the apparent intensity decrease is indeed the spectral shift? I really don't know. I'd think 250 watts is 250 watts.

I guess it makes sense though, since PAR values drop as bulbs age - which indicates less intensity. Should have thought of that.

[civil]

It is USING the same amount of energy, just not converting that energy into a form we use, light, as efficiently. I think it has a lot to do with how the energy excites the electrons in the gas and how many are available to be excited. Then if the electrons on a certain molecule are available. My thought is over time the molecules with the lowest energy or what can be excited with the least energy get used up or lose their electrons. There are now fewer available or only molscules that require higher energy to excite the electron to the next level, and then drop releasing energhy, light. So it uses the same energy we put in but it takes more energy to excite the available electrons and thus there is a reduction in intensity. I hope that makes sense.

[Graham]

It makes sense, but is it correct

As in, where does the energy go?
Do old bulbs run hotter? Inefficient use of energy is often given off as heat...if my mem'ry serves me well (which it usually doesn't). Actually, maybe the ballast would run hotter...

[civil]

There are different states of energy. Some electrons are easily excited, think of radiation, they practically blow themselves off the atom. Not the best example but you get the idea. So other take more, or less, energy to bump up to the next state. Like walking up stairs, bigger step take more energy. The size of the step has to do with the color released. This is really streching, it has been a while since I had this class. Energy conservation is still a rule but I can't remember exactly how it is used and changed in this exchange. If I get a chance I may have to dust off one of those text books.

[JJG]

Civil, sounds like your describing PPFD (Photosynthetic Photon Flux Density) the quality and quantity of light output from the lamps (not mine.... curtisy of Sanjay's research).

OK, 24 months is definatly time to replace the MH bulbs. Bulbs only I can do for $106 plus shipping at about $10-12. In a 90g tank do I want to replace the ballast with a PFO dual 400 and two 400w 10,000k Ushio's for around $330 plus shipping at about $40-45? HQI is pretty expensive and I question the return for the money. The two VHO actinics still stay.

The great lighting debate goes on. Will fresh 250 bulbs be enough to bring back the SPS color or will I really need to upgrade to keep happy SPS?
JJ

[geshields]

John,

I believe 400W'ers are the way to go...On my tank, I have 800W of halides (over a 36" width) and it is TOO much. My blue tort in my avatar wil attest to that.

On my new 180, I will be going with 3 400W Ushio 10K's on eBallasts and 4 actinics.

Greg

[Graham]

Yes, lighting is perhaps the most religious debate in the reefer's world....

I'd say that 400s are definitely not necessary for optimal coloration - but it depends on the particular coral and what spectrum bulb you are talking about. I ran 2-400W Ushios on the PFO HQI ballast and the color was pretty good, but I needed 4 VHO actinics (and would have liked more) to get most of the corals to shown the color I desired. Right now, I am running 4 250s, and couldn't be happier - well, OK, maybe a little happier.

Really, it's your call...see what other people have and what you like the best. There are a few huge threads over on RC in the lighting forum that discuss this ad nauseum and pics are often included.

[JJG]

Since the PFO 250 Eye ballast is matched to run the Iwaski 250s I'm locked into the 6500k bulbs.

I just changed the ballast in my other tank and discovered the bad news that the wiring was totaly different from the previous ballast. Had to completly rewire the hood, new harness, etc. The PFO dual 400 uses the same harness and mogul bases as I have now so all I would have to do is swap out the actual ballast and change bulbs. This is do-able, just $$

As to corals.....still starting over stocking the tank over the last month or so. It's whatever I can get a hold off plus planning on some Maxima's a little latter on once the tank has about six months or better.

Currently run the 220 watts of VHO Actinic for 15 hours, and 500 watts of MH for 9-11 hrs. 720 watts for minimum 9 hrs on the 90g. Even If I upgrade to 400/10,000k I would still run the Actinic morning and evenings (dawn/dusk) but not sure if I would still need to run them during peak. If not, this would help offset the increased power consumption. The debate goes on.... Planing on ordering tommorow, magic question is what??
JJ