New MH bulb question

Jasontkd · 02-25-2008, 12:43 PM

hey all, on my 29 gallon I am currently running a 150w phoenix 14k DE on a PFO hqi ballast and mini pendant. I just ordered a 150w reeflux 12k bulb because I have heard some great things about it. anyhow, my current bulb is about 7 months old. My question, do I need to raise my light up a little when I replace the bulb, or am I good to go?

Wiskey · 02-25-2008, 12:46 PM

I would,.. I mean in this senerio it's better safe than sorry

Whiskey

Jasontkd · 02-25-2008, 12:51 PM

that is true. I was just wondering with the spectrums being farily close and my current bulb not being very old, if it would make a big difference.

any suggestions on how high to raise it, and how much to move it back down and how often?

Jasontkd · 02-25-2008, 05:02 PM

^^^^^^

Wiskey · 02-25-2008, 05:19 PM

How high up is it now? How many hours per day are you running it? Is it on cables, or legs?

You could just cut the photo period back a couple hours, and increase it an hour a week.

Whiskey

Jasontkd · 02-26-2008, 10:09 AM

It is about 10 inches above right now, it is hung by adjustable cables, and I am currnetly running my t5 actinics for 9 hours a day and my MH for 8

Loverotties · 02-26-2008, 10:13 AM

Us your own judgment by how brite the reef looks and how the coral act.And I'd bring it down a little every couple days.

Wiskey · 02-26-2008, 12:19 PM

Quote:

Originally Posted by Jasontkd

It is about 10 inches above right now, it is hung by adjustable cables, and I am currnetly running my t5 actinics for 9 hours a day and my MH for 8

Oh wow! If it's already that far up I wouldn't worry about it. As a side note though lowering that down will greatly increase the ammount of light getting in your tank.

Whiskey

tdwyatt · 02-26-2008, 01:23 PM

You can demonstrate this with a PAR meter, new bulbs put out about 115% of their rated output (or more!) the first 100 hours of operation, so it is worse than you think if the bulbs are new. Regardless, the safe option is to start out with about 3 hours or less a day for 4 or 5 days to start with if you do not know what the previous conditions were, then increase every 4 days by about 20% until you get to 100% of your photoperiod at the end of the month. Another method is to keep your photoperiod at its normal setting, but use 5 layers of fiberglass screen suspended between the bulb and the specimens (make a rack between the edges of PVC pipe to support the screens), removing one layer every 4 days until you get to the point where you have unshielded light for your photoperiod. Another alternative is to raise your lights to about 2 feet bove the tank, bringing them own by 20% every 4 days until they are at their 4 to 6 inch final height from the surface of the water.

Many ways to skin a cat. Bill (fly guy) tells me they all taste like chicken once they're on the spit over the fire though...

HTH

tdwyatt · 02-26-2008, 01:24 PM

Quote:

Originally Posted by Wiskey

Oh wow! If it's already that far up I wouldn't worry about it. As a side note though lowering that down will greatly increase the ammount of light getting in your tank.

Whiskey

See the inverse square law for point source radiation for more on this.

Fly Guy · 02-26-2008, 02:13 PM

Quote:

Originally Posted by tdwyatt

You can demonstrate this with a PAR meter, new bulbs put out about 115% of their rated output (or more!) the first 100 hours of operation, so it is worse than you think if the bulbs are new. Regardless, the safe option is to start out with about 3 hours or less a day for 4 or 5 days to start with if you do not know what the previous conditions were, then increase every 4 days by about 20% until you get to 100% of your photoperiod at the end of the month. Another method is to keep your photoperiod at its normal setting, but use 5 layers of fiberglass screen suspended between the bulb and the specimens (make a rack between the edges of PVC pipe to support the screens), removing one layer every 4 days until you get to the point where you have unshielded light for your photoperiod. Another alternative is to raise your lights to about 2 feet bove the tank, bringing them own by 20% every 4 days until they are at their 4 to 6 inch final height from the surface of the water.

Many ways to skin a cat. Bill (fly guy) tells me they all taste like chicken once they're on the spit over the fire though...

HTH

Thats chihuahuas...not cats. Doug says they tase kid of ruff.

hey....Ive been looking for information on eggcrate........specifically par loss numbers with the tapered side up vs tapered side down. havient been able to locate it. Not even posting on that other board. You or whiskey have any ideas where to get this information? I know it exists somewhere......

now that the OT post is out of the way...jasontkd......be careful. I just downgraded bulbs.....seriously upgraded reflectors, was too agressive and fried more than a few corals. Personally , i suggst tapering it back as tom says and sdding 5 minutes a day until you are there......whatever you do dont take it for granted. It took many weeks for the damgae I did to truly be seen, by then it was too late and some of my corals will be paying for it for months