HQI vs. Mogul
 

I am looking into upgrading the lighting on my 75. Probably going to be a system built into the canopy with a mixture of T5's and MH bulbs. Are there any advantages of HQI vs. Mogul bulbs over the other? It sounds to me like most people prefer the HQI version.

It depends on the wattage that you need. I believe HQI comes in 70, 150, 250, and 400... the mogul systems come in 175, 250, and 400 (and higher) watts. The mogul bulbs don't require a glass UV shield, since the bulb is already shielded. Note also that electronic ballasts will run bulbs whiter / bluer than either magnetic or HQI ballasts.

The lights in question would be for my 75. I will mostly be keeping softies and LPS but would like to try a few SPS and maybe a clam someday. From what I have read it seems to me that the mogul base would be the better system except for the smaller number of choices for bulb wattage. I am leaning towards a 250 watt system but it may be a little much for me. The 175 watt mogul sounds like a nive compromise between the 150 and 250. Is there anyone out there that is happy with their 175 watt mogul system?

Thanks
Howard

It is not "HQI vs. mogul" but rather double-ended (DE) vs single-ended (SE) metal halide bulbs. SE bulbs are also referred to as "mogul" which is what the socket they fit into is called.

"HQI" is a type of ballast, just like there are "electronic", "pulse" and "probe" ballasts.

HQI ballasts put out more light than other nominally comparable ballasts, but they also use a lot more electricity. For example, a true "250W HQI" ballast will pull upwards of 320W versus 250W for a "250W electronic" ballast. HQI ballasts can run all DE bulbs and most SE bulbs.

How do you tell what kind of ballast you have? Take off the cover and look for the ANSI code. For example, a 250W HQI ballast is an "M80". The exception is electronic ballasts which don't have an ANSI code, but distinguishable by being much smaller and lighter than other types of ballasts.

The main advantage of SE bulbs over DE bulbs is the amount of PAR the gets into the tank since SE bulbs do not require an extra glass UV shield that DE bulbs do. SE bulbs seem to offer a slightly greater spread, but DE bulbs are more compact for tighter spaces. SE bulbs used to have more selection, but DE bulbs (at least at the 150W and 250W formats) have caught up in this regard.

AH yes, I forgot that part... the bulb matches to the ballast. My ballast is M85, and so are the bulbs that I buy.

Just out of curiosity, then... do/can electronic ballasts run both SE and DE bulbs at the given wattage rating?

Another point to note is the higher the Kelvin the lower the PAR (generally). If you don't want light demanding corals, then be careful your lights aren't too powerful. My tank is 24" deep, and I can't keep my LPS any higher than the sand or they will bleach form too much light. My lights are 2x250w DE with 20,000K low quality bulbs (I'm trying to keep my PAR down so the LPS are happier!).

If you're happy with lower light SPS (Montis, Digis, deepwater Acros) and lower light clams (Squamosa & Derasa) then you may prefer to have T5HO lamps instead of MH or lower watt halides (like 150s). I'm assuming your 75 gallon tank is 21" deep.

Yes, it is the common 21" deep 75 gallon. I have considered T5's but always come back to the MH systems. After reading the comments here I am starting to lean towards a 175w SE system with a couple of T5's running actinic (I like to run the actinics 1 hour at dawn and dusk). I will most likely have nothing but LPS and softies as I like the motion of the corals in the flow. Might try the odd SPS but nothing serious. I seem to be liking the SE over the DE bulbs. I am screwed up here or not?

To answer your earlier question, there are people who overdrive their MH bulbs... I've heard of running a 150W DE bulb on a 175W ballast. Many electronic ballasts can 'sense' the bulb it's connected to, and will run the appropriate amount of power ie: a 175W electronic ballast will run a 150W bulb at 150W. I don't think this goes for all electronic ballasts, however, and overdriving your bulbs will reduce their life.

I would definitely go no less than 150W with that depth of tank, if you aren't planning anything beyond LPS and softies that should be enough (though PAR values may be a little low at the sandbed). Remember also that just because there are 25 extra watts at the bulb (from a 150W DE) doesn't necessarily mean that you will get that much more light out of your system, this has more to do with the bulb and ballast combination than anything... a 150W 10K bulb on the appropriate ballast could easily produce more PAR than a 175W 20K bulb on a magnetic ballast, though the same may not be true of that same 20K bulb on an electronic ballast.

I went through the same thing when I started my tank... I was originally going to go with T5s.

umm if it helps i have a 55g tank about 20" deep and use one 250W 14000k single end bulb on a probe start ballast and everything seems very happy from my zoas and shrooms up to my squamosa montis and digitata and everything in between i know very little about light just that this one seems to work for me! :D

Never mind, answered my own question... anyone who wants to know, see this thread:

http://www.reefcentral.com/forums/sh...icecap+ballast

You can run any bulb which is rated for the nominal wattage of an electronic ballast. In other words, a 250W e-ballast can run all 250W MH bulbs. The downside to an e-ballast is that it will generally produce less PAR than a comparable magnetic ballast with the same bulb.

With respect to the OP's original question of 175MH, the best combination for maximum PAR is a 175W electronic ballast with the Iwasaki 15,000K bulb. This combo will give you as much PAR as many 250W combos while using less electricity than a 150W HQI system.

It's all a balance between looks (which is subjective), PAR output and electrical usage.

The best place to look up actual objective measured PAR values along with actual electrical draw is Dr. Sanjay Joshi's lighting guide:

http://www.manhattanreefs.com/lighting

Just pick your bulb and/or ballast and it'll spit out all the information you'll need in the PPFD (PAR) and Watts columns.

HL649, I Ran 2 250w XM 20k Mogul Bulbs on my 75G. I build my own xfmr using a probe start ballast. Worked like a damn. I still use the XM20k on my SPS tank and they grow well under that light.

If need be, you could always raise the lights from the top of the tank. That's what I had to do. It can be a bit of trial and error.. My current tank is 20" deep and my lights (250w 14K DE HQI) sit about 12 inches off the water's surface. That height seems to be just right for my SPS that are on rock work and my LPS'/zoos that are on the sandbed. I like the added bonus of having virtually no salt creep on my lights which I always hated when I had my lights lower. I haven't really heard from anyone who was overly disappointed with either light technology.

I'm a total halide fanatic, but I wouldn't run halides on an LPS tank. Too much light, plus you pay only a little less for a 150w or 175w halide bulb as you do for the higher wattages, so it just seems a waste. If I decided to make my tank LPS dominant again I would sell my halides and get T5s. I had an LPS tank recently that ran very well for 2 1/2 years with T5s. Most people would be surprised how little light LPS need in order to thrive. Many people over light them, and when they cut back lighting they experience much brighter colors. Besides, the T5 bulb choices give you lots of options for "color cheating". :D

my opinion
 

HQI double ended all the way!

I'll take DE over SE any day too! :D

this is kind of a grey area, MH is not to much light for LPS, but if you were using T5's for a long time they will take a while to adjust. look at the reef around austrailia and haiwii, there are LPS in 5 feet of water which are reciving more PAR than we could ever dream of putting in our tanks. the problem is most people don't have enough flow in there tanks to prevent/minimize bleaching. I have done exparaments after reading a few articles on bleaching and water flow and which a low flow rate of 20X turnover I could bleach the heck out of frags, but when I increased the flowrate to 120X I couldn't get them to bleach at all with all other conditions being the same.

now just increading pumps isn't enough, the trick is to spread the flow out all over so it ends up being a gentle current not a jet wash, I had a 94 gal tank with almost 12000 gph flowing in the display, but you could put your hand anywhere and all you felt was a gentle flow.. it took me about a week of screwing around with placment and such and I don't think you would ever acheive this with a sand bed (as the flow on the bottom of my tank was the same as the middle and the top) and you may have to be willing to rearange your rock to give you the best flow not the best look, but you could probable achieve both with a little more paitents than I have :biggrin:

Steve

If I am right in assuming you mean "DE over SE any day", then my question is why?

Grrr...I just replied, and managed to lose it. :twised:

Basically, I prefer the look of DE over SE. When I comment on someone's tank "Nice lighting", 9 times out of 10 it's DE powered by electronic ballasts. I also like the spotlight effect of DE which makes coral placement easier.

This is interesting. I have always struggled to get high flow without blasting spots, but I don't have the patience to mess around with it for very long, and I never seem to get anywhere anyway. I know my LPS are PO'd about my Wavebox, and it's been at least 4 weeks since I installed it, so you would think they would be used to it by now...??

hehe, and I will take a SE bulb over a DE anyday unless there is a space issue, the increased PAR and distrubution from a SE is to nice when it is run off the same ballast as the DE.

What I found is that I had to create natural low flow areas for the LPS, the hard part was making these areas as small as possible so I didn`t end up with an area 5 times the size of the coral with a lower flow. some times all it would take was a stratigicly placed rock to disrupt the flow enough for the LPS. then the trick was to make that rock look good while it is doing its job :mrgreen:

Steve

+1 and the fact that it is sometimes darn near impossible to mount a DE bulb in its holder without Herculean strength. With SE you simply twist your wrist.

But really, I don't see how there should much difference at all in the light produced by DE and SE bulbs notwithstanding the extra UV shield required for DEs. If you look at an SE bulb, it's pretty much just a jacketed DE bulb.

I have been leaning away from PAR lately...you can get great results without lighting the crap out of the tank. My LPS are all on the sand or the outskirts of the lights (my fixture is designed for a 36" tank and mine is 48" so the halides don't reach the ends very well...perfect for the LPS). They are all well colored. I changed the bulbs to cheap 20K to lower the Kelvin too. :lol:

it is and it isn't, the bulb is actualy a different design for the lighting element, not sure the exact differances, but I know operating temp is one as the outer glass and the gass inside it on a SE act as an insulater so the SE actualy burns a bit hotter, so maybe it creates a bit more efficiency?

the increase in PAR from a DE to a SE is small, and isn't realy the important part, rather the way a SE desperses that PAR over a larger area with out losing as much intensity is what I like. for example, you can light a 2X2 area with a 250 DE. with a 250 SE you could light a 3X2 area with pretty much the same effect on the bottom. Now having said that I ran two 250 watt SE's on a 3X2 area driven by M80 ballasts because I like light and lots of it :mrgreen:

so there are aplications for both, if I am making somthing with out a hood and I wanted a nice compact fixture I would probably use DE's but if I had to room for a hood I would go SE's. Presently I am concidering putting two 250watt SE fixtures on a 30 gal tank. but I am hesitating in setting it up as I realy want to go bigger, but not sure if I have the space for bigger.

Steve

you have to watch that, higher K bulbs don't produce less PAR, but rather PAR that is misread and reported as lower. PAR sensors over report PAR in lower K, IE the 6500K bulbs and way under report the amount of PAR in 20K bulbs. this has to do with the calibration to give you an average PAR level over a wide spectrum.. so by making it report properly under day light when we measure bulbs that have huge spikes of 380 to 420 nm it throws the average off as it isn't calibrated for that range specificly. so because of the nature of blue/violet light it can't read it properly and under reports it. the opposit is tru if you had a huge spike of green, the wave length of green overpowers the sensor and makes it think there is more PAR than there actualy is.

a practical example of this is about 6-8 years ago when everyone was running iwasakies and Ushios, then changed to the new radiums.. the radiums were listed as about 10% less par then the Iwasakis and about the same as the ushios, but people were bleaching corals left and right.

Steve

I don't know about that... red (yellow) light has more photosynthetically usable light than white light does, and blue light has even less. That's like grade 9 biology. :question: I don't know how that applies to aquarium bulbs since there are so many variables like amount of energy put into the bulb and different brands.

there is no white light, white is an effect from combanations of other light colors. thats why there is no white strip in a rainbow.

Photosynthetically Active Radiation or PAR, is from about 380 to 720nm and all forms of light can power photosynthis, the differance is what is more available and what plants have adapted to. If I remember right from hortaculture (corect me if I am wrong) red light will produce a fast growing but spindily plant, where blue light will make a slow growing but stockey plant. we did exparaments growing the plant under blue domanate light for root development and then switched to a red domanat light to increase folage and induce flowering.

Visable light starts at 400nm with Violet, and ends at 700nm with red in between we have blue green yellow and orange

you can produce a white looking light with different combanations of reds, greens and blues (primary colors) this is why we can get different PAR levels from white lights of different brands. one brand might have very high violet/blue and a spike of red and hardly any green and look white, another might have red, green, and blue all at the same levels and it will look white also.

as far as strenght of the wave lenght go the shorter the wave lenght, the more power it has, this is why blue light is domanate in deeper water and the green and red light gets filtered out.

Steve

This has been a very informative thread. Thanks to all that responded.

Well ya!! Maybe I should have put white in quotation marks for those detailed peoples. ;)

Yes, the sun in the fall is at an angle to the earth, and it creates a red light which is one of many factors in triggering plants of a later season to bloom. Blue light is in the spring, and fades to red as the year goes on.

Lots of information to learn on light, plants, corals, etc.[/quote]