buying better lighting

[SDW]

I have a 55 gal tank w/2 pc 65 w + 1-48" actinic light. I have a friend who works for a electric supply shop which is going out of business. So, here's my question, is it possible to buy a MH fixture/ballast from them and use it over a fish tank. The lfs said no because it would not have enough Kelvin, but what if you used a MH bulb specific for aquariums. Anyone use a diy mh and had good results? THANKS in advance.

[jerryc]

Yes you can use the ballast,Thea or at least for most part the same
you will just have to get a lamp from a lfs or on line.
If you look hear http://www.hellolights.com/ you can see
the same ballast for sail that you get at a Electrical supply

[dakar]

Sure is.... if you can post the manufacturer and part number of the ballast sand, I'm certain we can cross reference out exactly what you got and give you more direction from there.

[SDW]

looking at some of the items at that web site you listed, brought up another question. Would I be better off to use a MH light with lower watts or up my pc...I currently have pc 65w x2 and a 40w actinic. If I bought another pc ballast and set that would put me at 260 total watts, or would it be better to buy a MH 175 and maintain my 40w actinic=216 total watts. Didn't mean to write a book.

[PurpleAardvark]

It really depends on what you want to do. If you are going to do soft corals, zoo's and mushrooms than PC are ok, for SPS corals the metal halide is the way to go. Watts really do not mean that much for intensity/brightness. A 175w metal halide will put out more light than 260w worth of pc. But you can also over saturate you tank with light as well. Recent studies on corals have show that there is a current trend of putting to much light over your tank.
There is a point to were you will stunt your corals growth or even kill it. The recent PAR trend which I hate so much has proven to be a flop as predicted. Par is how alot of people have be mesurring light output from a bulb. Bulbs with a praticular high red zone are actually stunting and killing corals because well high red conitations cannot be fended off by most corals. Most bulbs with high par ratings (XM 10k to name one) have a particually high red consitration. So know that I have hijacked your thead, sorry by the way, try providing us with what your plans are for the tank so we can give you a better suggestion for lighting.
To go a little firther for all you par fallowers or junkies in some cases, anther down fall to the whole par thing is it is completely inacurrate. In theory it was a good idea but the par meter was the down fall. By moving a par meter 1/4" in any direction you will get a different reading. So the test results given are also inacurrate. Even if you averaged out the par it would not give you a relable test because of the drastic differences. I know there will be a different wave coming soon (how soon I do not know) that will messure the full spectrum of colors and intestity of it, which will once again change how we buy bulbs. In short be on the look out for new articals to come about par, red wave intesity effects on corals, aqua cultured corals and studies on corals that are overly lit.
Anther thing to keep in mind overlighted coral that are stunted are more prone to desiese (RTN, WBD, ect...)

[PurpleAardvark]

:hijacked:

[davejnz]

I agree,photoinhibition is a real thing and i've experienced it first hand.

[Whoyah]

PurpleAardvark,

I am curious how you evaluate bulbs if you don't use PAR or watts?

[PurpleAardvark]

I take a close look at the spectrum chart and look at the lumman output, yes lummens don't messure the full spectrum but the test are alot more accurate than the par meter. I have also done alot of trial and error. The bulbs i am using now are the Giesmann 22.5 megachrome HQI 250. The have a nice balence of spectrum and output plus I am having the best growth rate I have ever had on my sps. For size of bulb I look at the depth of the tank and what I plan to put in there. For a tank that is 24" to 30" deep which is what I have I like the 250 HQI's. There is another consideration which I feel not to many people take into consideration about there tank is what you put on the bottom has an effect on you light too. A 4" sand bed not only takes away 4" of depth but if kept clean will reflect more light than crushed coral or bare bottom.
So to answer you question in short about evaluting a bulb I feel it more nessisare to look at all the info rather than just a part such as par or watts. Believe or not the is some 175w metal haides that put out more light than some 250w of a different bulb.

[davejnz]

Yes,I agree that spectral output is the most important aspect when evaluating a bulb IMO.PAR/watts is overated,you can grow corals with 4x40w NO flourescents
with a quality tube like the G.E. 6500k.Although i like MH,I no longer recommend them for shallow tanks.I've learned the hard way about photoinhibition(250w saki over my shallow 40 breeder),I was stubborn for the longest time.I didn't wan't to admit that its possible to overlight some corals.My experience tells me that it is possible and probably happens alot more than most of us realise.Just like 175's can be brighter than some 250's,4x54w T5's(when overdriven on an IC660) produce more PAR than even DE 250's.PA makes a good point about the PAR sensor.MH's being a point source light aren't capable of flooding the tank with an equal/balanced light output.I think Grim Reefers PAR tests comparing the 2 different systems prove that.The differences in PAR readings were dramatic when he moved the sensor just inches away from directly under the 250DE pendant.He tested the way i would like to see Sanjay as well as others test.Useing reflectors,having the sensor placed 19" underwater in a real life application rather than no reflectors in a black box.