dawgdude;454089 wrote: That depends, do you want to over drive the bulbs and have the put out more par and be whiter? Then go with magnetic......which also pull substantially more power than the 250w that they say.
If you want a bluer look to your bulbs with slightly less par then go with electronic. I prefer electronic.
ichthyoid;454100 wrote: I thought the IceCap MH ballasts had the highest PAR? Did I misunderstand? I seem to remember reading that in S. Joshi's articles (could be wrong on this, would'nt be the first time).
Perhaps they were just highest PAR of electronic design ballasts? Can't remember, please advise. Thx
Mockery;454105 wrote: An HQI or M80 ballast (I don't remember if there is a difference) will give you the most par, due to the fact that they overdrive the bulbs.The 250 PFO HQI's use up to 380 watts just depends on bulb. Since its using so many more watt it will produce a stronger light and in turn more par.
ichthyoid;454076 wrote: That being said I am a big fan of electronic design, in general. With few exceptions, an electronic design is generally more efficient all around. High frequency in particular, combined with electronic designs has some distinct advantages.
Skriz;454122 wrote: I kind of disagree here. Let me see if I can explain. It all comes down to how you see/define efficiency. The e-ballasts waste less power, so a 250w ballast uses only 250 watts and produces a certain amount of par (x) per watt. Magnetic Ballasts waste some power, so a 250w ballast mY use 300 watts, and produces x par per watt. The magnetic produces more par per watt used (1.3x), thus is better at producing par than the electronics. For me, that makes the magnetic "more efficient". You can also pick up used magnetics for CHEAP, making the payback period in energy savings close the day before never.
If your concern is power consumption, e-ballast is the way to go. If not, magnetic.
You can check the "efficiency" I'm referring to in Sanjay's charts (I think).
ichthyoid;454208 wrote: In reexamining Sanjay Joshi's MH ballast/lamp evaluations (below)-
I can see why one might be led to conclude the 250 watt magnetic ballasts are more efficient, looking at S. Joshi's 'data'. But lets take a closer look at what he looked at. Only one type of bulb (Iwasaki 6500) was evaluated, with only one ballast each, from four different companies. This is statistically only slightly better than flipping a coin. In fact, the data can not be conclusive for anything.
To further challenge the above conclusion, the 400 watt ballasts were tested with 4 different types of bulbs, and yielded almost the exact oppoosite conclusion: that the 400 watt electronic ballasts both produced more total PAR/PPFD (one exception), and produced more PAR/watt (no exceptions).
The 175 watt ballast/bulb cmparison included 2 lamps and 2 ballasts with opposite results for each of the 2 lamps. Again, meaningless.
Additionally, the study only allowed each bulb to warm up for 20 minutes before measurements were taken. The 'proof' that the bulbs had stabilized was determined by current/power measurements on each lamp. It is widely accepted in the lighting industry, that a lamps spectrum and irradiance cannot be considered to have stabilized before 100 hours of total operation. In fact, all irradiance specifications that I have ever read, were made afte 100 hours operation of the lamps. Also, I have read that Metal Halides in particular, do not 'settle in spectrally' until they have been running for several hours.
The above combined with almost no 'population' to study (one of each) means we are again left to wonder what might have been.
http://www.personal.psu.edu/faculty/s/b/sbj4/aquarium/ballast%20comparison/ballast-comparison.html">http://www.personal.psu.edu/faculty/s/b/sbj4/aquarium/ballast%20comparison/ballast-comparison.html</a>[/QUOTE]
Let's do take a close look at what he looked at: [IMG]http://www.manhattanreefs.com/lighting">http://www.manhattanreefs.com/lighting</a>
As you can see, he tested more than just a single 250w bulb and 4 x 400w bulbs. You'll also notice how many different ballasts he used.
Now, his methodology is by no means perfect, but it does give some pretty decent numbers/data to work with.
Rbredding;454109 wrote: mounting the ballasts can also be an issue.. an electronic 250W MH ballast weighs about 7lbs. the magnetic version of the 250W ballast weighs about 13lbs
(ok, my numbers might be off, but you get the point... the magnetic are much heavier than the equivilant electronic.)