MH vs. CF

V

vmahaffe

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Dec 10, 2006
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Rochester, MN
I was just wondering what everyone thinks about metal halide vs. compact flourescent? I recently bought a coralife metal halide fixture and am replacing my current CF's. I was told that I only need to run my 150wx3 MH for about 4 hours/day to get enough light for my plants. The 4x96w bulbs will be used just so that I can see my fish. What does everyone think about the 4 hours of light? Would it hurt anything to blast my plants with the full 834w, other than maybe some algae?
Thanks.
 
Cycle your lighting with timers so that the MH's represent the brightest part of a the day and the CF around that for a total of 10 - 12 hour days. It will be an artificial daylight tank. Plant florish in the cycle.
 
midiamin said:
Cycle your lighting with timers so that the MH's represent the brightest part of a the day and the CF around that for a total of 10 - 12 hour days. It will be an artificial daylight tank. Plant florish in the cycle.
Click to expand...
So maybe run the CF's for about 4 hours, then turn them off and run the MH for 2-4 hours then off and then the CF's 4 more hours or just leave the CF's on for 10-12 with the MH's on simultaneously for 2-4?
 
Let it match the natural day/night cycle. Brightest during the height of the day. You can run them both if you want during that time. Your a better judge of that than someone who does not know your exact circumstances. i forgot to ask if you have indirect sunlight hitting the tank
 
Not much indirect sunlight. You pretty much answered my question. I didn't know if it woudl mess anything up by running that many watts on the tank at once. I am going to look for a timer that can run multiple plugs. I have 3 plugs for each MH and 1 for the CF's.
Thanks for your help.
 
just an fyi the more watts per a gallon for your plants means the more co2 that will need to be added...
 
vmahaffe said:
I was just wondering what everyone thinks about metal halide vs. compact flourescent? I recently bought a coralife metal halide fixture and am replacing my current CF's. ...
What does everyone think about the 4 hours of light? Would it hurt anything to blast my plants with the full 834w, other than maybe some algae?
I was told that I only need to run my 150wx3 MH for about 4 hours/day to get enough light for my plants. The 4x96w bulbs will be used just so that I can see my fish.
Click to expand...
vh:

IMHO forget the literature.

I have a virtually identical situation with a 110G tank.
I had 260W of CF - three 10000K bulbs and one 7100K bulb
I now have 260W of CF - two 10000K bulbs and two 7100K bulbs
and 300W of MH - two 14000K bulbs

The 4 hours is IMHO an internet myth which is principally read and subsequently propagated by folks who have no experience or have not experimented with all options.

I run my configuration 10 to 12 hours per day.


Three Items to Note:
  • [1] I believe that the comparison of MH watts and CF watts is invalid as
    • [A] the phosphor in CF bulbs produces gaps in the energy spectrum emitted and as such the MH provides a better quality of light; and
    • some energy in CF bulbs is usurped due to fluorescing the phosphor

  • [2] At 5WPG nice plants can be grown without CO2 injection. The problem is that too little fertilization inhibits plant growth and and too much fertilization yields excess nutrients both of which generate algae. The appropriate concentration of the various ferts as well as their dosage rate takes some experimenting in order to preclude algae production.
  • [3] Should you decide to "blast" your plants please do so slowly (I slobbered up here). Ten hours of MH light the first day and the continuance thereof will melt vals and cause other plants to suffer although they will recover. If I get into this MH introduction again I will start with two hours the first day and increase the MH lighting duration an hour per day thereafter.

TR

BTW: I believe (this belief is very qualitative but is based on experimentation) that minor CO2 injection, such as that produced by DIY two liter soda pop bottle, significantly increases the range of fertilizer concentrations and dosages which generate plant health and growth but which does not generate algae.
 
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