How Deep Do T5's Pentrate

K

KaniRyde

New member
I'm upgrading to a 110T and its 30" deep. I currently have a 50 gallon that is 20" deep with a 250watt HQI that i had to raise from ten inches from the water to fifteen inches from the wate due to heat issues. My 50 gallon is 3ft wide but the 110 gallon is 4ft wide so I will need to buy another MH or switch to T5's. I'm afraid that heat may become and issue with two MH but I'm also worried that if i switch to T5's they may not penetrate deep enough for my SPS which I have about 20 or more.

I moving over to the 110 gallon tank because I have no more room in my 50 gallon and when i was looking at a 120 and 180 gallon tank at my lfs one of their customers offered me his for free he just moved to a 300 gallon.
 
Watt per watt, T5s generate more heat than good metal halides. People often believe the reverse is true (probably because T5s are cooler to the touch). But the fact is that although the heat is more disperse there is more of it. Also, IMO fans are easier to use with MHs because they are less restrictive on airflow above your tank (assuming you use pendants or retrofits instead of a spanning fixture). So as far as heat issues go, I think you'll be increasing them by adding T5s again assuming you'll stick to the same total wattage. On the other hand, T5s penetrate deeper than MHs. One of the biggest problems with MHs is that their light output is highly variable from one spot to the other. This is due to the fact that it is basically a point source of light. Fluorescents do not suffer from as much attenuation of light with depth as do metal halides because their light is spread. Overall, MHs and T5s are pretty evenly matched in terms of pros and cons. It is best to consider your situation.

In your case, I would spring for a strong, high-efficiency T5 fixture like an Aquactinics or even better a retrofit Icecap setup (8x 48" would work nicely). Don't skimp on the cooling fans as this greatly affects the lamp output and life. 2 MHs would work, but you'd probably need 400W ones for such a deep tank. Unless you are willing to spring for an automatic light mover (which is a nice option btw), you won't get a very even spread with a MH setup on a tank of such dimensions. This might result in some patchy growth with SPS. T5s would be better all around.
 
larger tanks tend to require a chiller, for many reasons, not the least of which is all the light, but the volume of water to surface area of the tank, and the additional pumps needed for all the additional flow and equipment.

T5's could probably manage 30", but I wouldnt expect massive light at the sand bed. 30" is way into the 400w MH range, some crazies might even swing it to 1000w. T5 is probably out of its element in that situation. you would need alot of them, thats for sure.
 
30" with enought bulb.

T5 add less heat to the water than halide, but you need to ventilate the bulb for better output
 
If you are running a canopy a 8x54 watt Ice Cap system will give you as much light to the bottom of the tank as most 250 watt halides. That should be enough light for a good mixed ref, just keep the high light stuff up off the sand.

I have ran T5's and Halides, Halide cause more heat issues than even the overdriven T5 systems.
 
Physically speaking, at least, MHs generate less heat Watt per Watt. This comes from the fact that they generate more light per Watt than T5s (~110 lummens per Watt vs. ~90 lummens per Watt). However, doing this comparison is difficult when you look at setups with different overall wattages and fan placements/orientations. IME Metal Halides do not necessarily create large heat issues if well setup. For instance, I have a 250W MH hanging over a 37gallon acrylic aquarium. With the light on, the temperature averages 1 degree over what it was with the lights off. However, this is mainly due to the fact that I have 2 4" fans blasting over the top of the tank and possibly from the fact that the light is on a light mover (which keeps it from heating just one area). In any case, I think the Icecap is the best way to go with your particular system if you are using a canopy or willing to build one.
 
Sounds like T5's are the best for a 30" depth because upgrading to 400w MH is out of the question. One thing that I can't seem to find out is how often do you have to replace T5 bulbs compared to MH bulbs, T5 bulbs seem around $20-30 a while MH range from $50-90. Thats comes to $160-240 for 8 T5's and $100-180 for 2 MH.

Also how close to the water do you normally keep T5's. I know these questions are repetitive but the search engine doesn't always work and it take hours search through this forum to get the answer your looking for. Later today I'll try to post a picture of the tank and the setup so you can see what I'm working with. The stand and the canopy are one solid piece.
 
Last edited:
aninjaatemyshoe

When you say Icecap are you talking T5's Or MH? Another question, how do you have your fans blowing on your canopy, is it left to right or back to front? How much room do you have between the MH and the water? And what is a light mover, is there a link to a site that sells them?

I had more questions than I realized.
 
<a href=showthread.php?s=&postid=10056121#post10056121 target=_blank>Originally posted</a> by aninjaatemyshoe
Physically speaking, at least, MHs generate less heat Watt per Watt. This comes from the fact that they generate more light per Watt than T5s (~110 lummens per Watt vs. ~90 lummens per Watt). However, doing this comparison is difficult when you look at setups with different overall wattages and fan placements/orientations. IME Metal Halides do not necessarily create large heat issues if well setup. For instance, I have a 250W MH hanging over a 37gallon acrylic aquarium. With the light on, the temperature averages 1 degree over what it was with the lights off. However, this is mainly due to the fact that I have 2 4" fans blasting over the top of the tank and possibly from the fact that the light is on a light mover (which keeps it from heating just one area). In any case, I think the Icecap is the best way to go with your particular system if you are using a canopy or willing to build one.
Click to expand...

Heat is a byproduct of a fluorescent lamp, it is a needed component of halides. Halides are designed to run hot. Also one of the major factors in heating the tank is infrared light output and halide produce much more than typical fruorescent lamps.

As far as lumens per watt it really doesn't matter in the case of heating a tank. Take a 90 gallon tank as an example. Most people would suggest a 2x250 watt halide system over that tank. a 6x54 watt T5 system would be the T5's of choice for the same tank. 324 vs 500 watts.

Practical experience is the best indication of the difference. I had a overdriven 6x80 watt T5 system on a 125. Those lamps were overdriven running at just over 600 watts. Running in an enclosed canopy WITH THE GLASS LIDS ON MY TANK the water temp never hit 81 degrees. Running 3 150 watt halides in an open top, NO LIDS OR CANOPY with the fixture a couple inches above the water heated the tank to the same temp the T5's did (and produced a lot less PAR). When I converted the fixture to 3x250 watts and raised it to 7 inches above the tank (and added a fan) I lowered the house thermostate 2 degrees because the tank was reaching 82 degrees.

I agree with you on one point, if you set the halides up right a lot of times you can get by without a chiller but if heat is an issue T5's are the way to go.
 
The lumens per watt is an indicator of how much visible light is produced from a bulb. Bulbs generate heat, visible light, and other electromagnetic radiation (heat in this case could be considered infrared radiation). Neglecting the electromagetic radiation that isn't part of visible light or heat (such as UV, radiowaves, etc.), you have a question of how much heat vs. how much visible light is generated. Energy in equals energy out; therefore if more visible light is produced per Watt, less heat/infrared radiation is produced per Watt. Physics aside, you make a valid point which is what I stated earlier - you don't typically use the same wattage when you go from one setup to the other. You've obviously had better luck with heat issues with T5s, I've also used both and have had better luck with MHs on the same tank. If you can manage to provide good air circulation for a T5 setup with fans (or have a fixture that does so), then I see no reason why you couldn't avoid bringing in major heat issues. I was just stating from my experience that it is easier to keep a pendant MH lighting setup from heating a tank than it is to keep a restrictive T5 fixture or canopy. I was also trying to correct what I believe to be a misconception about T5s vs. MHs, which is that they produce less heat Watt for Watt.

To answer the other questions: I was speaking of the Icecap T5 retrofit setup meantioned earlier - which is a wonderful setup if you use plenty of fans and good design consideration. The light mover is an automated system that moves my MH pendant across the tank. I bought mine off eBay for $100 (retails around $200). The product website is here: http://www.lightrail3.com/

T5s are typically placed much closer to the water than MHs (4"-6" as opposed to 8"-12"). But this is a product of what I believe to be the biggest downfall of MHs - that the light they produce (and also the heat) is so highly variable from one spot to the next. For me, the light mover more or less resolves this problem and produces a nice effect. I can place the light much closer to the water because I don't have to worry about it generating too much heat/light in one spot and potentially bleach a coral (or even possibly damage my acrylic tank). It has even been suggested that varying the light location in such a manner provides added benefits. One of the obvious benefits is that it provides for light at parts of the coral that would otherwise be shaded. Another possible benefit as stated from the Reef Aquarium Volume 3: "The periods of rest provided by the passage of clouds can be measured in changes in the rate of photosynthesis, thus for the coral and zooxanthellae these clouds are akin to rhytmic breaths. Since the rest periods afford a reduction in the photosynthetic rate, they also provide a reduction in the formation of toxic oxygen free-radicals... designing a lighting system that is non-static provides a way to keep the photosynthesis within its normal bounds." This is why I ultimately went with MHs as acheiving this effect with T5s would be rather difficult.
 
Thanks for all your help. i've narrowed it down to the 48" 6x54W SLR T5 Very High-Output Retrofit Kit w/ Bulbs totaling 510watts for $609 @ ReefGeek and the Mini Pendant System - 2-250W 14000K+ HQI Phoenix @ 500watts for $569. Which of the two would you recommend for my tank. I appreciate your opinions.

Here is a picture of the tank it is 48x18x30
 
problem with light movers is the reliability. I have used or seen in use many different HID light movers (growing plants). Most did not last past 6 months with out major mods and repairs. I know out of 6, none made it past a year.
 
aninjaatemyshoe is right. T5s do tend to make more combined heat than halides of the same wattage, but its a small thing to consider, all things considered: If a light source were able to convert 100% of the incoming electricity to light, it would be in the 400-500 lumens/watt range, as even the most efficient light sources like halides are still only able to convert about 1/4 of their electricity to actual light... the rest is EM, noise, and heat... but mosty heat. So arguing about percentages of efficiency, considering both are going to be making gobs and gobs of heat compared to the light they produce, is futile. With either, fans are the best way to use evaporative cooling to the fullest advantage.
 
Very true, when comparing T5s with MHs they are very close in terms of efficiencies. The efficiency consideration is more pertinant when comparing them with say PC lights or horribly innefficient incandescents and halogens. The latter two are a great waste in energy even for common household use.
 
<a href=showthread.php?s=&postid=10055803#post10055803 target=_blank>Originally posted</a> by Icefire
30" with enought bulb.

T5 add less heat to the water than halide, but you need to ventilate the bulb for better output
Click to expand...

exactly.

why would one say that t5s heat the water more than mh?


show me some scientific evidence and I might beilieve it...
 
Uggh, have you been reading this thread at all, hornk? How about I ask the reverse, explain to me how T5s, which produce less visible light per Watt than MHs, produce less heat watt for watt than MHs? Simple thermodynamics: Energy in equals energy out. Again I reiterate, however, that the comparison is not usually apples to apples. People tend to run MH setups at higher wattages than they would T5 setups on the same tanks. Ultimately, the heat that enters into the tank is more dependant upon the airflow you have around the fixture (eg. fans) than it is on the individual efficiencies of the bulbs. I've personally used two setups of comparable wattage in MH and T5s and have noticed lesser heat issues with my MH. But this is probably more due to the fact that of the two setups I was more successful in providing good circulation with the MH.
 
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