How often should I change my Halide Bulbs

[Dana Riddle]

I live in Colorado and I had an assignment to value a grow facility. I went to about 10 facilities and called about 5 more. All used HPS, MH and MV to supplement their sunlight greenhouses. About half invested in LEDs and took them off... a few said that I could come by and have all of the LED units that I wanted for free. A few had some 10-12 bulb T5 units. Now 15-16 places is not all of them in the world, but these places are highly profitable and in business to make millions so their experience was telling to me.

Marijuana facilities?

 

[jda]

Hemp too. Even the non-THC stuff is very valuable for other CBD uses.

 

[Dana Riddle]

It is often difficult to understand what works for one hobbyist might not work for another. It is often a matter of seemingly small things. I'm not trying to discount experiences of ours.
Metal halide lamps are considered point sources of light - there is often a relatively small spot of high intensity light with more or less concentric patterns of decreasing light intensity. When changing lamps, the intensity can increase suddenly up 2 or 3 times. Some corals in this new hotspot will receive a great deal of sudden radiation while those at the outer edges of light intensity might not see a great increase. Some corals have zooanthellae that are highly adaptable to fluctuating light fields - other do not do well subjected to light increases. The height of the fixture above the water level plays a critical part here. So does lamp burn position. And reflective surface in the fixture (say, polished aluminum v. white paint.) There are photopigments that offer protection against excessive light (xanthophylls.) These are produced in response to high light, In low light, they are not produced thus offering little protection against high light.
Metal halide lamps often produce UV-A and UV-B radiation, especially when in 'base up' positions in pendent fixtures. This UV decreases as the lamp ages. So does the content of UV-absorbing compounds that offer protection against 'sunburn.' Plastic 'splash guards' can absorb almost all UV, while shields made of glass do not. Age of the plastic matters. UV-absorbing compounds can be baked out of the plastic. This is sometimes associated with 'yellowing' of the plastic. If changing a lamp with a glass guard (or not guard at all) UV radiation can potentially increase dramatically. An analogy would be a fair-skinned person laying on a Hawaiian beach for hours without a sunscreen.
IMHO, acclimating a coral to a sudden increase in light is the prudent thing to do. In the early years of reef keeping, it was advisable to raise the fixture when changing halides, or somehow adjusting the light intensity. Many LED luminaires now offer an 'acclimation' mode. Gimmick or valuable asset? It's your decision.

 

[Centerline]

I use two 250 watt Phoenix 14k de run off ice cap ballasts. Currently 9 months of use with plans to change at 12 months. This is my first halide setup so I was curious when everyone else changes theirs?

Been running 250 Radiums for years. 10-12 months (though I have let them go as long as 18 months and still saw growth) and as suggested acclimation to new bulbs is best.

 

[leepink23]

It is often difficult to understand what works for one hobbyist might not work for another. It is often a matter of seemingly small things. I'm not trying to discount experiences of ours.
Metal halide lamps are considered point sources of light - there is often a relatively small spot of high intensity light with more or less concentric patterns of decreasing light intensity. When changing lamps, the intensity can increase suddenly up 2 or 3 times. Some corals in this new hotspot will receive a great deal of sudden radiation while those at the outer edges of light intensity might not see a great increase. Some corals have zooanthellae that are highly adaptable to fluctuating light fields - other do not do well subjected to light increases. The height of the fixture above the water level plays a critical part here. So does lamp burn position. And reflective surface in the fixture (say, polished aluminum v. white paint.) There are photopigments that offer protection against excessive light (xanthophylls.) These are produced in response to high light, In low light, they are not produced thus offering little protection against high light.
Metal halide lamps often produce UV-A and UV-B radiation, especially when in 'base up' positions in pendent fixtures. This UV decreases as the lamp ages. So does the content of UV-absorbing compounds that offer protection against 'sunburn.' Plastic 'splash guards' can absorb almost all UV, while shields made of glass do not. Age of the plastic matters. UV-absorbing compounds can be baked out of the plastic. This is sometimes associated with 'yellowing' of the plastic. If changing a lamp with a glass guard (or not guard at all) UV radiation can potentially increase dramatically. An analogy would be a fair-skinned person laying on a Hawaiian beach for hours without a sunscreen.
IMHO, acclimating a coral to a sudden increase in light is the prudent thing to do. In the early years of reef keeping, it was advisable to raise the fixture when changing halides, or somehow adjusting the light intensity. Many LED luminaires now offer an 'acclimation' mode. Gimmick or valuable asset? It's your decision.

Thanks for the input, I decided to go ahead and change bulbs and raise the fixture. I been experiencing some new sand algae which prompted me to consider changing the bulbs.

 

[GarrettT]

So par from a 10k bulb dropped 70% over 3 month period? Am I reading the chart correctly?

If so, this would mean that a 6500k bulb would have 4x the output of a 10K bulb after a 3 month duration, which is pretty substantial.

 

[A. grandis]

So par from a 10k bulb dropped 70% over 3 month period? Am I reading the chart correctly?

If so, this would mean that a 6500k bulb would have 4x the output of a 10K bulb after a 3 month duration, which is pretty substantial.

The whole system adapts fairly quick to to the new bulbs. One year is the rule of thumb to change halide bulbs and T5s. When we change we just adapt the system to the new bulbs slowly. There is absolutely no problem doing that. Never had!
I don't move my halide fixtures up or down when changing bulbs. I prefer to reduce photoperiod accordingly. For a photoperiod of 5 hours a day using the halides we can bring down to 3 hours a day for the first 5 days or so, than add one more hour after that for 5 more days, etc.. I've even changed from 175W bulbs on e-ballast to 250W Radiums on M80s without any problems doing that. It's much simpler than we might think, practically. Main thing is to make sure that the application is correct to the system, using the right fixtures and tempered glass lenses.

 

[RedoubtReef]

I used to run Phoenix 14Ks. Ran them about 8 hours a day with a 1 hour staggered start between the 2 for that 'sunrise/sunset' effect so it ended up with each bulb running 7 hours. I don't know that I'd do it again. I would change out bulbs every 12-14 months. Never changed the run time or height and had no issues with the change out.