MH conversion Help

[cousenfl]

I want to convert my 55 gallon tank over to a reef tank and was told that 2- 150/175 MH lamps would do well for soft and hard corals. I was wondering if MH only would be fine by or if I need to include some CF? Also what is the difference between pulse start and non-pulse start? As far as dispersing heat are pendants better then using a hood? What would be the better MH bulbs double ended or mogul base? What color 10000K or 20000K? Any help would be helpful.

 

[snakeblitz33]

Metal halides are great when dealing with SPS corals, they have a high Par and Lumen value, however they do produce a lot of heat, the ballasts are extremely large and bulky and will also cost you quite a bit of more money per month in electrical costs.
to answer your questions:
1. If you only have 10k metal halide bulbs, then you will need to supplement their spectrum with an actinic light.
2. Pulse-start MH lamps do not have the starting probe electrode (Figure 2). Instead they have a high-voltage ignitor that works with the ballast to start the lamp using a series of high-voltage pulses (typically 3 to 5 kilovolts). Without the probe electrode, the amount of pinch (or seal) area at the end of the arc tube is reduced, which results in a reduced heat loss. Furthermore, using an ignitor with a lamp reduces the tungsten sputtering by heating up the electrodes faster during starting. Warm-up time is also reduced. Pulse-start technology was developed to increase lamp life and to have both the energy efficacies of high-pressure sodium (HPS) lamps and the desirable color characteristics of MH lamps.
Traditional metal halide (MH) lamps use probe-start technology. Three electrodes are present in the arc tube of a probe-start MH lamp: a starting probe electrode and two operating electrodes (see Figure 2). To start the lamp, a discharge is created across a small gap between the starting probe electrode (also called the starter electrode) and the operating electrode. Electrons then jump across the arc tube to the other operating electrode to help start the lamp. Once the lamp is started, a bi-metal switch removes the starting probe electrode from the circuit.
http://www.lrc.rpi.edu/programs/nlpi...ProbePulse.asp

 

[snakeblitz33]

3. Pendant or canopy? Your choice - they put off the same amount of heat - it's just whatever you want your aetetics (sp?) preference is. I personally like canopies. However, most pendant MH's are HQ (double ended).
4. Neither HQI nor Mogul socket based metal halides have shown significant difference in lamp spectrum and intensity. Now, if you are looking at money and conveinance, I would suggest going with a mogul socket. (this is a screw in bulb)
5. The spectrum that your corals need depends on what corals you keep. 10k metal halides generally grow corals very quickly, but the colors are more brownish. Under 20k metal halides, the corals grow slower but have a ton more color. If you would like color and growth, try either two 150w mogul socket 14k metal halides or two 150w mogul socket 10k metal halides backed by two 460nm T5HO actinics.
Then again, I am not a lighting expert, and you should do some serious research on your own about your lighting choices. By the way, corals grow just as well under 6 T5HO's for your size tank or even four 4ft VHO's for your size tank as well. Look into all sorts of alternatives before you invest so much money in metal halides. Now, if you are just wanting the "shimmer" look on the bottom of the aquarium - then you will have to go for the metal halides because they are a "point of light." instead of a strip. Anyways, I'm babbling. I hope I helped you out.

 

[snakeblitz33]

Don't say thankyou or anything. I hope you re-checked your thread to see the posts. blah.

 

[jetskiking]

The spectrum that your corals need depends on what corals you keep. 10k metal halides generally grow corals very quickly, but the colors are more brownish. Under 20k metal halides, the corals grow slower but have a ton more color. If you would like color and growth, try either two 150w mogul socket 14k metal halides or two 150w mogul socket 10k metal halides backed by two 460nm T5HO actinics.

I want to hit on this point a little. I totally agree that the 10k grows quicker and the colors appear more brown under that light. However my expierience is its just visual. I personally believe that what actually happens is the color increases but is just not visible under the spectrum. When I pull corals out of my frag tank lit with a 10k and put them in my display under 14k they display some of the most vibrant colors. This will fade away over time if I leave them in the display. Another example of this would be coral retailers. Ever notice how vibrant a lot of WYSIWYG corals are and they don't hold the color once you get them in your display. This is because most of them were grown uder 10k or less and just the pics were done under 20k.

 

[snakeblitz33]

ok, jetskiking, you do make a point, however from an aquarists viewpoint - are you seriously going to change out your lights or corals every other day to see the new colors pop out or are you going to leave the same lights on the same tank and look at the same corals? IMO, I am speaking about long term effects. Not short term, where you put the corals under a certain type of light to take decent florescent pics... 10k or less lights brown out corals - or makes them look more natural.
You could also argue that you should only put shallow water corals under 10k lights, mid-level corals under 14k light and deep water corals only under 20k light because that is the spectrum of light that they are mostly used to.
Remember - in any case - half of the intensity of the light is lost within the first six inches of water...

 

[jetskiking]

Originally Posted by SnakeBlitz33
http:///forum/post/3146711
ok, jetskiking, you do make a point, however from an aquarists viewpoint - are you seriously going to change out your lights or corals every other day to see the new colors pop out or are you going to leave the same lights on the same tank and look at the same corals? IMO, I am speaking about long term effects. Not short term, where you put the corals under a certain type of light to take decent florescent pics... 10k or less lights brown out corals - or makes them look more natural.
You could also argue that you should only put shallow water corals under 10k lights, mid-level corals under 14k light and deep water corals only under 20k light because that is the spectrum of light that they are mostly used to.
Remember - in any case - half of the intensity of the light is lost within the first six inches of water...
I'm definetly not arguing just stating some observations to add on to what you said. You are correct that as a hobbiest you are not going to change lights or move corals just to color them up. It does make a good arguement to running 10k's with actinics supplement though instead of 14k or 20k.

 

[snakeblitz33]

Ah, sorry, I thought you were arguing. It must be just my defensive nature. (I grew up in private school, that's my excuse!)
Good addition to the knowledge here. Thanks.

 

[cousenfl]

I got busy and just checked back to see replies sorry I reply sooner. If I understand correctly the best route to take would be to go with the 10K and supplement with cf if I want the best color and growth! Thanks for the help but now I think I have more to think about before I proceed. Any other input will also be appreciated.

 

[snakeblitz33]

Originally Posted by cousenfl
http:///forum/post/3147407
I got busy and just checked back to see replies sorry I reply sooner. If I understand correctly the best route to take would be to go with the 10K and supplement with cf if I want the best color and growth! Thanks for the help but now I think I have more to think about before I proceed. Any other input will also be appreciated.
Ah, finally! lol. Good to see you have some direction. Don't misunderstand me, I didn't say that either was the best, I just offered an option. It's up to you to research and find out what is best for your system and your corals.