Metal Halide Q&A

I would be happy with 75 but it never hurts to offer a little less in cash

 

hey dingo, great thread, and seems like the place to go with MH questions! Hoping you can help me out, I bought a used set up and its time for new bulbs. I've got two 250w MH and two t12 VHO's to work with. ARO electronic Ballasts. 75 gallon tank.

I was looking at buying phoenix 14k's thinking since they are white with blue tint I could run them without the actinics.

Would it be better to run a whiter bulb (10k?) with the actinics? The t12s are purple in color, not blue. I believe they are UVL super actinic bulbs

If anyone has a similar set up let me know what you use, thanks!

 

from my understanding 10k is better for coral growth but 14k is more eye pleasing with a blue tint....id go with 10k and actnics....and supposedly 6500k is the best temperature bulb for growing most corals but is the least eye pleasing

 

I have a friend who was Reefkeeping mag's TOTM a few months ago. He runs two 250w halides with VHO like you. His tank looks just AMAZING.
If you have SE bulbs then I recommend Radiums, if they are DE then i recommend Phoenix 14k. Both bulbs look very similar and work quite well without supplement. As for your VHO's, you can put whatever you like in here for supplemental lighting (either actinics or full spectrum or a combo of both, your choice here). But with the two halides listed above you will not "need" supplementation to be happy with the colors of your tank.
Sounds like you have a pretty good lighting setup going on there btw!

 

ive heard that you get better coral growth with 10ks though(is this true) so if looking for fast growth and appeal wouldnt the 10k with actnic supplements be better but if growth rate isnt an issue and you want less equipment then the 14ks?

 

contrary to popular belief this is incorrect.
Growth is based on how much light is put out in a coral's required spectrum. The reason why some corals grow faster under 10k is that the levels of supplied light are higher with the 10k bulbs (but not always). However, the quality and uniformness of the spectral output here is more of a dictator of growth compared to only color temperature itself.

 

Bulb spectrums confuse me i understand for a reef tank between 6500 and 20000 are necessary with 10000 and 14000 being the most ideal. im so confused lol, i thought i was starting to grasp it

 

thank you! They are SE, but i saw phoenix makes the 14k in SE, just a little pricier than the DE.

I wasn't sure if the purple of the UVL VHO's would look bad with the phoenix since its bluer

This is my first time around the block so idk what looks good lol

 

you are talking about color temperature or kelvin. 6500k is yellow, true 10k is perfect white, 14k is icy white, 20k is blue, and 50k (only one bulb out there with this kelvin) is essentially pure blue.
But the kelvin of a bulb is just what the human eye physically sees as the end product of all the different wavelengths being put out.

So when each bulb creates the ark and excites the elements in the reaction chamber, photons (light) is produced from the electrons of the elements becoming "excited" and then releasing the photons when they become less "excited". So each chemical will produce a specific wavelength range of photons that it releases. Your bulb will be releasing all these photons and each one will have a specific wavelength when its released. Now measuring spectral output will actually look at each and every spectrum that is put out. This can be combined into a nice graph that will show the levels of each at a given time. So you will get all these wavelengths (from 400nm to around 700nm) that are being released in different quantities by different elements at the same time. The combination of all these specific wavelengths blending together will give you your final kelvin or color temperature.
Example: A ushio bulb will put out a very excellent range of wavelengths but will not have high values in the blue (450nm) range so it appears more white than say a radium which puts out equally significant levels of wavelengths but has a high output of 450nm photons. This causes the radium to look more blue... even though their spectrums are somewhat similar.

Did that help or just make things more complicated? lol

 

The SE phoenix are not near as good as the DE versions. I would recommend radiums for SE use.
For your VHO's, I am personally a fan of the purple because is touches on the violet wavelength and gives more intense color... trade off: your tank will look different than what your used to. Some cant stand it, some love it and for some it doesnt make a difference. I would say to get one actinic and one purple to start with to see if you like the color. Its really something you have to feel out for yourself. (but the purple, IMO, does give good colors)