WTB: MH lighting for 30g
- Thread starter Deanos
- Start date
bad coffee
Inept at life.
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Deanos,
Since it's a 3' long tank, and most MH pendands cover around a 2' square, you're going to need to make a choice:
Put the light at one end, and have a bright side and a dark side of the tank
Put the light center and have dark edges.
Raise the light up to cover both ends, and in doing so, A: lessen the intensity getting into the tank, and B: light up the surrounging area.
If you go with a 400 watt, you could easily rais it up and have enought light for the depth, but you'd have to mask the light from lighting up the whole room. But, it should be high enough so you don't get a lot of heat issues.
Also, remember that light follows an "inverse Square" rule.
E= I/D^2
E= Intensity
I= Candellas (we'll use watts just so it's easier, even though it's not exactly right.)
D= distance
at 1' away:
E= 400/1^2
E= 400
at 2' away:
E= 400/2^2
E= 100
I did at at 1 and 2 feet away from the tank just for easy math. who ever puts a 400w MH 24" above the tank on a 30 gallon?
So short answer, the 400w may be a better bet to raise up so you get both ends of the tank lit. You just have to cover the light spill.
Any questions?
BC
Since it's a 3' long tank, and most MH pendands cover around a 2' square, you're going to need to make a choice:
Put the light at one end, and have a bright side and a dark side of the tank
Put the light center and have dark edges.
Raise the light up to cover both ends, and in doing so, A: lessen the intensity getting into the tank, and B: light up the surrounging area.
If you go with a 400 watt, you could easily rais it up and have enought light for the depth, but you'd have to mask the light from lighting up the whole room. But, it should be high enough so you don't get a lot of heat issues.
Also, remember that light follows an "inverse Square" rule.
E= I/D^2
E= Intensity
I= Candellas (we'll use watts just so it's easier, even though it's not exactly right.)
D= distance
at 1' away:
E= 400/1^2
E= 400
at 2' away:
E= 400/2^2
E= 100
I did at at 1 and 2 feet away from the tank just for easy math. who ever puts a 400w MH 24" above the tank on a 30 gallon?
So short answer, the 400w may be a better bet to raise up so you get both ends of the tank lit. You just have to cover the light spill.
Any questions?
BC
- Location
- The Big City
BC
I have the oppsite problem my fixture is a little longer than the top of my tank. Would it be better to lift the lights higher over the tank or leave them closer to tank, which I have them right now. Will I lose intensity by raising them, I don't have any problem with heat with the lights being that close.
Michael
I have the oppsite problem my fixture is a little longer than the top of my tank. Would it be better to lift the lights higher over the tank or leave them closer to tank, which I have them right now. Will I lose intensity by raising them, I don't have any problem with heat with the lights being that close.
Michael
bad coffee
Inept at life.
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Actually deanos, the only prob you'll have is lighting up the room with the 400. You could build a 'skirt' to go around the pendant. That way it blocks out light. If you do the math, and have the light 15" above the tank, you're only loosing a little bit.
(e=400/1.25 or 320 watts, which is more realistic.)
I would personally go with the 400 if you can get a good deal. my single 150 was $150 used. but new it was over $300. So it's a trade off. Spend lots more money on two fixtures, or a little cash ($20 or so) on something to cover the light.
(something I just thought of, if it's a pendant, you could open it up and bend the reflector. That way you could direct the light more into the tank.) that may be the easiest way yet!
Mike,
If you're not having problems, you shouldn't have to raise your lights. In fact, if the fixture is longer than the tank, you can lower the light and get more intensity. I hear corals like that! Watch out for heat issues if you get them too close. Also, putting the light fixture in the water is a bit too close IMO.
BC
(e=400/1.25 or 320 watts, which is more realistic.)
I would personally go with the 400 if you can get a good deal. my single 150 was $150 used. but new it was over $300. So it's a trade off. Spend lots more money on two fixtures, or a little cash ($20 or so) on something to cover the light.
(something I just thought of, if it's a pendant, you could open it up and bend the reflector. That way you could direct the light more into the tank.) that may be the easiest way yet!
Mike,
If you're not having problems, you shouldn't have to raise your lights. In fact, if the fixture is longer than the tank, you can lower the light and get more intensity. I hear corals like that! Watch out for heat issues if you get them too close. Also, putting the light fixture in the water is a bit too close IMO.
BC
A skirt eh?!
!? Now I have to get my girlfriend involved...this may be just the way to get bring her into the "Fold".
On a serious note though...do you mean a fabric type of material? I can't visualize anything suitable AND aesthetically pleasing.
Dean
On a serious note though...do you mean a fabric type of material? I can't visualize anything suitable AND aesthetically pleasing.
Dean
After doing some "research" on nano-reef.com and RC, forget the 400w idea. My tank is full of zoos, shrooms and LPS; those guys would probably bleach under that much power.
BC: pm me about the skirt idea though, my 10g has a pendant over it which has some light spillover. Thanks!
Dean
BC: pm me about the skirt idea though, my 10g has a pendant over it which has some light spillover. Thanks!
Dean
bad coffee
Inept at life.
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The skirt is something that hangs down below the end of the pendant. You could make it so it's permanent, or it just slips over the top of the light.
the skirt can be anything. You could use aluminum foil, tinted glass, wood, styrofoam, aluminum flashing from HD. Then just finish it the way you like it. One thing to think about is how much heat the light puts off. If it's a pc hood, you could probably get away with plexi. However, for a MH, i'd go with something more heat resistant.
BC
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