mh question ??

[jetchris]

Ok the mh's that i have are old and i need new ones. It seems that my mh's get extremly hot. So my question is , is there some mh bulbs that do not put out as much heat as others, or are they all about the same?? If there are some bulbs known for not putting out as much heat as others, then what is the brand. Also if you had the choice between 15k and 20k which one and why , I dont really understand the whole "k" thing. Thanks

CHris

 

[vettesarebest]

I don't think there are any manufacturers that make a less "Hot" bulb. All MH's are going to me extremely hot. As far as the Kelvin rating of the bulbs it is all about preference. Do you have actinics? A bulb with a K rating lower will be more white/yellow and therefor it will have more Par. The lower the K rating is the faster the corals will grow but they will not be as colorful. A bulb with a higher K rating will give the corals more color but it sacrifices that color for growth. It is a trade off.

 

[mojo]

Pretty much what he said - all bulbs are about as equally hot.

A higher kelvin bulb is bluer, and a lower kelvin is more yellow. 10k is about neutral white, where 15k is blue white and 20k is blue.

"K" is actually suppose to be "kK", for thousand Kelvin. It's the apparent color of a black body at that temperature. If you heated up a piece of iron, for example, to 10,000 degrees Kelvin, you'd have roughly the white color of a 10k Kelvin bulb. Since iron (or any metal, for that matter) melts far before 10,000 Kelvin, it's only an approximation.

 

[vettesarebest]

So.... That little piece of Iron in the bulb gets to 10,000 degrees?

 

[mojo]

umm... no. It's a theoretical model. Any black object that gets to those temperatures supposedly would burn those colors. Nothing that exists on this planet will get to those temps without evaporating (at least not under normal conditions).

There's no iron in the bulb - it was just an example metal.

 

[wbholwell]

A) it's not iron, and
B) it doesn't get to 10,000k deg. K

 

[wbholwell]

ah, beat me to it, mojo

 

[vettesarebest]

Wellllll, I feel REALLY DUMB! Somehow I always seem to make a somewhat "Smart" comment but then I ruin it with a stupid one.

 

[cgill311]

Maroons15;37074 wrote: So.... That little piece of Iron in the bulb gets to 10,000 degrees?

No no...Kelving rating as relates to the wavelenth (or color) of light is totally different from filament temperature See this http://www.3drender.com/glossary/colortemp.htm">link </a>for more info.

Actually there is no filament in a metal halide bulb. Light is emitted via excitation of gaseous mercury molecules in the presence of an electrical potential. The "metal halide" term comes from the metal halide compounds added to the mercury vapor to affect the spectrum of light emitted. See [IMG]http://www.infoplease.com/ce6/sci/A0859290.html">here</a>.

 

[wolfie]

wow you guys really know how to Highjack a post


ON the note of which K buld to get, then it all depend on what you want and what you also have running with your MH...

If you also run VHO/T-5, or PC and are using actinics for those buld then you be better off with the 10K bulbs..

Reasion for that is because you already have actinics running so any higher rated K bulds are not going to change the color of your tank and 10K will help your corals grow better then the other K rated.

 

[jetchris]

cool thanks everyone, I am now well educated on kelvin - so what is the difference between a T5 light, pc and actinic. I have an enclosed canopy and my tank is about 6' long and there is 2 ea mh's on either side so there is a pretty good gap in the middle with no light. So if I get 2 ea 250 watt 14k bulbs - what would be ideal to put in the middle ??? I am looking to keep mainly soft corals.

Thanks again for your replies

 

[vettesarebest]

T5's are the new rage and are small "florescent like" bulbs that have virtually no heat. They are good for any coral but you will have to have a lot of them. PC stands for Power Compact which is a "High Output florescent" bulb. These are larger than T5's and generate more heat. Actinic is only the "Color" of the bulb. You can buy a actinic anything. Actinic PC, Actinic MH, Actinic T5. Actinic are used for bringing out more color in the coral. A couple people have actually had a successful tank with only actinics.

Correct me if I'm wrong please.

 

[wolfie]

Why do you want to go with MH when you just want to keep solf corals?

MH will cost more money to run them and they put out a lots of heat.


If you still want to use MH then you may want to run 4 T-5 bulbs on the side. Move the MH closer together and run 2 T-5 each on each side.

With this much lights you can keep everything in that tank, unless it a deeper tank the normal.

 

[vettesarebest]

Trust me you'll want to keep hard corals!

 

[jetchris]

wolfie the tank came with MH, i will prob buy some sps - but i actually like the look of soft corals better. thanks maroon for your replies