T5s vs. MH... What would be the ultimate faceoff?

[thriceanangel]

OK the link doesn't work now, but its a robot.

[NyReefNoob]

ok after reading all of this. i currently have a 62g tank 36x24x17 and i have been using t5's for 6 month's. never measure pars ect. i have a mixed reef 1\2 lps 1\2 sps. i currently use 3 tek retro's that are about 7" off the water. with light combo of bulbs 2 and 5 are 10k's 3 and 4 are geissman 11k's and 1 and 6 are giessman antic plus. chose this route to cover a broader light spectrum. i have great color and growth from this. one thing people dont take into consideration is sand color. white sand works as a reflector. just my two cent. great test though cant wait for the results

[plack]

I would Test At Tank Depths of 8" 16" 24" And add for EACH type( VHO/ T-5 /M.H.) The Depth under the bulb to the tank's top !!!!!!!!!

:-)

Paul

[plack]

woops...

[plack]

[mouscacha]

I'm eagerly awaiting the results. I'm building a 90 and haven't purchased lights for this reason.

Another test I would like to know is what the temp increase on both lights would be. I live in Hawaii where it never dips below 77F. I would definitely take the 4" handicap into account.

[jazzmanb]

shimmers,shimmers,shimmers....until t5 can give off shimmers,theyll be used for actinic...the shimmer effect alone kills t5 in my opinion..t5 does give you great color option and what not,but i personally am not a t5 guy,i dont get the still water look,regardless of par and color..my 7 cents..

[jamesdawson]

Why not have both MH and T-5 if you have room for both. MH for the lower K, "punch" and shimmer, T-5 for for the higher K and very uniform coverage they offer. Best of both worlds IMHO.

James

[thriceanangel]

I "get" the cheaper, cooler, more efficient, better coverage aspect of T5's. What I don't get is using a hotter, less efficient, more expensive bulb just for "shimmer." I currently am running MH only on my system, and the shimmer is nice. But I certainly wouldn't choose MH OVER T5 just for that reason. I have a MH because I got a great deal, and there isn't a viable T5 option for my tank size. But the shimmer effect only goes so far. Using a combination MH and T5 is probably the best option, but why do it when a properly reflected T5 bank alone is enough? Are you going to add an extra 350-500 watts over a 4' tank just to see lines? I guess some people have that option, and to others the shimmer effect is worth everything, but the flip side is that the most cost effective, efficient solution is the most appealing solution.

[hahnmeister]

Actually, the heat output of halides vs. T5s is about the same, and I wouldnt say T5s are more efficient exactly. It depends on alot of things, like spectrum and reflectors. A 3000K halide will smoke the output of a 3000K T5HO. A 10,000K halide will also outdo a midday/aquablue combo of T5s. T5's real advantage is in the blue range. So the real 'it' combo for the best of both worlds would be to use 10,000Kish halides for your daylight, and blue+/actinic T5s to suppliment. Thats how I do it, and I have an SPS packed 125g thats doing great with less than 500 watts of light.

[thriceanangel]

I'd have to disagree with you on the heat aspect. My 250w is completely untouchable when on up to 15 minutes after being off. My T5HO's I can unscrew immediately after turning off, well almost immediately. My water temp fluctuation with T5HO is minimal. With the halide I have to turn off my heater in the summer, not so with the T5's. I mean the inner glass on a DE MH gets to around 3000*F I believe, whatever it is it's HOT! My T5's probably get to 200*F.

And actually I think the actinic T5 isn't the best IMO either. But I do and did agree that a MH teamed up with T5's are the best option, just that it's not the most efficient. BTW Hahn don't you utilize a light mover? That is a great way to boost efficiency, and I hope to get one for the next tank (240 cube).

[danskim]

I think maybe he meant heat per watt or something. A t5 setup takes several bulbs, while an MH bulb is by itself producing all the light (and heat).

[The Grim Reefer]

I've ran both halides and T5's over the same tank. There is absolutly no doubt the halides caused the tank temp to go higher than the T5's.

[danskim]

Yeah that's what I experienced too. I forgot to add in that the reason a halide would be hotter to touch is because all of the light is from one bulb with a smaller surface area than a number of T5 bulbs.

[hahnmeister]

I'll have to correct you then about the heat aspect. Watt for Watt, T5s will be the same if not hotter than halides. The reason that they are cooler at any given point is because they have 40x the surface area per watt compared to a halide. 250 watts of halide is contained within a 4" long by 1" diameter jacket. 250watts of T5 is spread across 16-18 linear inches of 5/8" diameter tube. Both are giving off about 200 watts of heat... its just that the T5s are more spread out. FWIW, I have had a harder time cooling with T5s on some tanks than halide... 250watts of halide leaves alot of open water space above the tank for airflow. 250watts takes up more area and can create a 'pocket' of air between the bulbs and the water surface which can heat the tank up more. With either though all it takes is a fan to compensate.

Now if you feel that you can get away with less wattage with T5 than with halide (keep in mind that ballasts will vary the actual wattage and therefore heat output with both... a 250wattHQI can easily run 320-250 watts), then its a different story.

[The Grim Reefer]

Originally posted by hahnmeister
I'll have to correct you then about the heat aspect. Watt for Watt, T5s will be the same if not hotter than halides. The reason that they are cooler at any given point is because they have 40x the surface area per watt compared to a halide. 250 watts of halide is contained within a 4" long by 1" diameter jacket. 250watts of T5 is spread across 16-18 linear inches of 5/8" diameter tube. Both are giving off about 200 watts of heat... its just that the T5s are more spread out. FWIW, I have had a harder time cooling with T5s on some tanks than halide... 250watts of halide leaves alot of open water space above the tank for airflow. 250watts takes up more area and can create a 'pocket' of air between the bulbs and the water surface which can heat the tank up more. With either though all it takes is a fan to compensate.

Now if you feel that you can get away with less wattage with T5 than with halide (keep in mind that ballasts will vary the actual wattage and therefore heat output with both... a 250wattHQI can easily run 320-250 watts), then its a different story.

You can correct all you want but that doesn't make you right

My fixture was originally 450 watts of halides and 168 watts of PC's. All lamps were behind a 6 foot long UV shield. That heated the tank more than a 6x80 watt overdiven T5 system that was just over 600 watts. The T5's were in a canopy and ran for a long time with the glass lids on the tank. The halides were open top no lids. The bottom of the halide fixture was about a quarter inch closer to the water that the T5 lamps, that wouldn't make much difference.

[thriceanangel]

I'm definitely with Grim on this one. There is no comparison. My T5's barely heated the tank, and my MH makes it bordering on chiller time! And the MH even has a remote ballast, and the T5's didn't. I don't care, you can spread out 3000* over 10 feet and it's still going to be WAY hot! 40x times the surface area or 400x and you'd be getting closer to the amount of dissipation you'd need.

[hahnmeister]

Well, what sort of air movement were you using with each one?

According to calorimeter tests, the T5 and halide technologies make about the same amount of heat (T5s actually make slightly more, which makes sense, since their light output is slighty less at the bulb). If the halides had the as much fans as a T5 setup, they should cool just as well, if not better (more open water area). There are too many variables here to argue... something as simple as what skimmer you were using then vs. now, or a change in circulation pumps could also account for the change. Either way, we are arguing about pretty small variances here. The most efficient halides still are converting about 75% of their electricity into heat. The most efficient T5s are converting say... 80% into heat... so we are talking about ALOT and slightly less of ALOT. It really comes down to the fixture and the ventilation method of the tank more than the lighting technology itself. We are comparing 80% of 600 watts to 75% of 650... whoopie... either way, you are still putting a 480-488 watt heater over your tank. Either one could heat your tank up well over 100 degrees if not dealt with properly... so how you deal with it will mean more than if its T5s or Halides.

From my dual 40B setups, where one was lit with a 250wattDE and one with a 6x39wattT5, the T5 tank heated up much more when the lights were on compared to the halide. Both were open top, and the halide left more open space for cooling while the Tek made a pocket of hot air across the entire surface of the other tank. The halide tank was a happy 80 without a fan, while at the same time I had to add in fans to cool the T5 tank or it sat at 85 degrees.

[jamesdawson]

Well, IME T-5s transfer less heat to my tanks' water than MH. My chiller comes on much less with the T5s.

I always thought it was because the entire heat load from the MH is so intensely concentrated in such a smaller area (radiating out from the much smaller bulb and particularly down into the water, kinda like a heat lamp or a laser) and this means there is less opportunity for the heat to dissipate before being absorbed by the water.

Whereas the heat load from T-5s is so much more spread out because of its greater surface area that a greater percentage of its heat dissipates up and away from the water and less is absorbed by the water than the MH.

I know that in theory and reality both shed alot of heat, I just think the higher intensity of the MH heats the water more than T-5s if all other things (ventilation, ambient air temp, etc) are equal. I also think its easier for fans to dissipate (blow away) heat off T-5s into the air than it is to do the same for MH.

Just my 2 cents, although it would be interesting for Sanjay to put forth his wisdom on this subject.

James

[The Grim Reefer]

If you place 2 150 watt blow dryers 6" above a tub of water and 300 watts of curling irons 3" above which will make the water heat more in 10 hours?

[danskim]

Haha interesting analogy-thing.

[barjam]

Shimmer effect makes my wife sick to her stomach, no idea why. Also my tank is in my media/movie room. Shimmer would be distracting.

[danskim]

I never really missed the MH shimmer when I went all T5.

[hahnmeister]

Actually, Grim has illustrated my poinnt quite well with his analogy.

Lets just say that 500watts of T5 was put in a canopy, and then 500watts of halide was put in another, both over say... 75g tanks. No ventilation, no holes, nada.

Both are going to create about 400watts of heat. Since the heat will be trapped inside the canopy, the water will be heated by either light system, and to about the same level.

Where things vary between those of us who have had better experiences with halides, or better experiences with T5s is in how we have ventilated the fixtures above our tanks. Both units can create enough heat to kill everything in our tanks, but its how we deal with each system's heat output that makes them different. For me, I had my halide on an open top tank in a pendant... others may have theirs in a canopy, or part of a combined fixture that covers the whole tank. When I needed cooling for the halide tank, it was just a matter of adding a clip-on fan blowing across the surface. With the T5s, I had to add a cross-flow fan or blower to get things in check. Either system could have been enough to overheat the tank in a warm room if it wasnt for the fans, but in my case the T5s required cooling at a point much sooner than the halides. Some others might have other experiences, and others have ones like mine. It really doesnt make a difference, I just think that the idea that many people throw out there that T5s are cooler just because they are cooler at one spot is bogus.

Grims analogy can be interpreted many different ways because we dont know how they are being used, or what direction the blow dryers are being faced in. The blow dryers may be facing upwards, in which case, who cares. The blow dryers may be facing the water, in which case, they will transfer more heat than a iron being held above the tank. Both the curling irons and the blow dryer could be contained within a canopy... in which case either one would provide 300watts of heat to the water below (and if you count the effects of convection, the blow dryers with the air movement would actually heat the water faster). My point is, its really in how you deal with the heat more than how much heat they make... at least, I think thats why some have had such varying results. But I wouldnt go attributing either light source as being hotter or cooler than the other. They are really very close, and considering the scale, the amount they will actually vary is a tiny percentage. Im sure that whatever you guys may think is either hotter or cooler is merely an attribute of the reflector of fixture you were using, and how you were using it rather than the actual bulbs of either technology (or perhaps another factor that is being overlooked... like the removal of that extra maxi-jet powerhead that contributed 10 watts of heat that was at the same time that you changed lights). With the analogy that Grim made, in an ideal situation, neither would contribute any heat to the water below either 300watt heat source because heat rises if given the chance. Perhaps my experience with T5s was not as good as some others (or my experience with halides was just that much better) because my SLS Tek wasnt able to shed heat upwards as well as my halide pendant... instead, it trapped heat between the lights and the water. Im sure that if some of you took a closer look at either system, there would be things you could do to handicap or improve either to the extent that the actual bulb's contribution would be easily manipulated... T5 or halide. Maybe I wouldnt have had heat problems with the T5s at all if I had used an Aquatinics or ATI fixture. Then again, maybe some of you wouldnt have heat problems with your halides if you used Lumenarcs with built in 3" ducts. First law of thermaldynamics says that energy can neither be created or destroyed, and so if either light source uses 250watts (or really more like 275 vs. 277 like it was in my case), and one light makes 85 lumens/watt at most, and the other makes 90 lumens/watt at most... the rest is heat... and considering the efficiency of even the 90 lumen/watt light will still mean 80% of its energy is going to heat... its hardly worth comparing. What goes in must come out.

One thing I would like to point out though, jamesdawson, is that the more spread out an energy source (or lack of one in the reverse for cooling), the better energy will cross that barrier. The laws for convective, radiant, and conductive heat transfer in thermaldynamics all back this up. This is why in Europe, rather than a single large probe shaped heater with a 300-500 watt element inside, they can get away with a 50 watt cable buried underneath the gravel and heat the same size tank. So T5s, with their larger area covering more of the water (and closer I might add) are actually presenting themselves as a better heating source than halides with their point source of heat. The larger the area that heat can be transferred over any given substance, the better it will transfer energy... just like... say... light or electricity. So halides, covering a smaller area of water than T5s have a more difficult time heating water because they have a smaller space to transfer heat with. Think of radiators on a car, or computer.... the larger the interface area, the better the transfer. And being that either source is heating, not cooling, the T5s are at a disadvantage. Also, since halides leave more space over the water open, this space can be used for cooling... something that T5s leave much less of. I suppose the best way to think of it is T5 fixtures are a bit like a greenhouse... trapping heat under them.

With either one, air movement is going to be the critical element.

But when people go touting T5s as cooler than halides, I start to hack and cough.

[danskim]

Whoa that was a long post.
I don't know as much as you about all the technical stuff, but I think it's worth noting that most people's experiences with MH and T5 show that their tanks run cooler with T5. Although it's true that some people do change up their cooling system along with new lights, but for those without canopies, this usually isn't the case.

My experience backs this up. I had a 2x250w MH + 4x96w PC Hamilton fixture with an acrylic shield. There were two fans in the fixture that moved air inside the fixture away to one side. I kept the fixture about 6 inches above the water.
I moved to an 8 bulb TekLight that is 4-5" off the water. Before I put a fan (because I wanted to increase output, not because of heat), my chiller was running a lot less than it did with the MH setup.