metal halide photo period
- Thread starter qasimja
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It really depends on how powerful the halides are, what color temp of the bulbs (ex- 10K is stronger than 20K), how far they are from the tank, type of reflector, etc.
If you are in doubt, list how many and what wattage the T-5's are, and the above info on the halides, then someone can make an educated reply.
Thanh is right about the average. However, if you have weak T-5's and then put the coral under strong MH, you stand a good chance of causing them to bleach or cooking them entirely.
The BEST way, is to measure with a PAR meter. Then multiply PAR x hours. Duplicate the 'PAR*hours', and you are golden.
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well i had the corals under 6 bulb T5s on the old tank from 10-7pm the new fixture is 3x 250W mh and 4X 96W pc actinic and their about 4-5 inches above the water
Edit: more specifically they were under a nova extreme pro fixture
Edit: 6x 54W
Edit: more specifically they were under a nova extreme pro fixture
Edit: 6x 54W
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Once acclimated to the new stronger light you can run them long as you like, Just have an off time part of the day. I ran 3x 400 watters on my 150 for 14 hours each day.
FWIW-
I have done a rough calculation on where I would begin with photoperiod using your new light system based on your feedback above.
Old (T-5) set up was:
324 x 9 hrs. = 2916 watt*hrs
New (MH+PC) should be (approx):
1134W * X = 2916 watt*hrs, so
X = 2916W*Hrs/1134W
X = 2.6 Hrs per day with the MH+PC system to begin with.
You may gradually begin to increase photoperiod after a week to 10 days.
*Disclaimer-
This is based on an ASSUMPTION that the PAR per watt of the two lighting systems is about the same (it will not be). The above 2.6 hour photoperiod should be a pretty fair starting point. A PAR based calculation would be far better (more accurate) to use.
The new light is 3.5 x's what the old one was. So, the time should be 9 Hrs/3.5 = 2.6 Hrs per day. I did it two ways and got the same answer (a proof).
Also,
If you start at ~2.6 hours per day, that is 156 minutes.
Once you begin to increase the photoperiod, after at least a week, I would not increase it more than about 10% per week.
That would mean;
156 min X 0.1 (that's10%) = 15.6 minute increase per week
In round numbers, you could start out at 2 1/2 hours, then increase by 15 minutes each week. This will work as long as you keep the amount of light below the photoinhibition limit of the corals you have.
Photoinhibition is the amount of light which, if exceeded, will begin to harm the corals.
If you start at ~2.6 hours per day, that is 156 minutes.
Once you begin to increase the photoperiod, after at least a week, I would not increase it more than about 10% per week.
That would mean;
156 min X 0.1 (that's10%) = 15.6 minute increase per week
In round numbers, you could start out at 2 1/2 hours, then increase by 15 minutes each week. This will work as long as you keep the amount of light below the photoinhibition limit of the corals you have.
Photoinhibition is the amount of light which, if exceeded, will begin to harm the corals.
If you can, you might also consider lowering the amount of light, say by raising the fixture or only turning on some of the lights at first.
The reason for this is that, in simple terms, corals produce toxic compounds during photosynthesis called peroxides (yes, similar to THAT peroxide).
A certain amount of peroxide is produced per unit time, depending on the amount of light.
Giving the corals less light gives causes them to produce less peroxide per unit time. This is easier on them.
Later you can begin lowering the light back down. or increasing the time it is on.
This is called a 'rate limited reaction' for the chemists out there.
The reason for this is that, in simple terms, corals produce toxic compounds during photosynthesis called peroxides (yes, similar to THAT peroxide).
A certain amount of peroxide is produced per unit time, depending on the amount of light.
Giving the corals less light gives causes them to produce less peroxide per unit time. This is easier on them.
Later you can begin lowering the light back down. or increasing the time it is on.
This is called a 'rate limited reaction' for the chemists out there.
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i'l going to stick with the reduced photo period i left the lights on for 3 hours today and they were fully opened and looking good so i will do 3 hours for the first week or so and go from there Thanks for helping
Edit: oh also the lights are 6" above the water right now
Edit: oh also the lights are 6" above the water right now
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<p style="text-align:left">I run my halide for 9 hours and i get great growth and everything seems to be happy. I run acintics hour befor during and hour after
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ok just a little update all the corals are responding great to the new light except this torch coral when the lights come on it looks like this at first it gets better but it doesnt look flowing like when the lights are off or when i had it under t5s any suggestions?
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