I have had every light so far I think. I started with PC's and went to a 4 bulb T5 over my 55 and now I have two 150 MH HQI with two Actinic VHO's. With all the lights so far I dont see a real advantage to T5s so far. Watts is watts so without a PAR meter no one really knows if 210 watts of T5 gives you more than 210 watts of MH right? So with this I ask whats the advantage you see to each? I dont see that T5s run that much cooler either...so lets hear the fight start!
I believe that energy costs are the mail concern, followed by bulb cost and bulb life. I like the convience also of having several different spectruns of light over the same tank area. The popular shimmer of MH lights has never been a real plus for me, but some folks think it's the way to go. I can compare the 3-250wt MH with 8-VHO's I have over my 200gal with the 8-36" T-5's I have over my frag system to be very similar. Some will argue the depth of the tanks being different, but the distance from the bulbs that the corals are placed is almost the same. Personally I will be using T-5's on any new tank setup till something better comes along.
I like my halides. I got a great deal on them used or I would have gone with straight t5's. My wife and I like the shimmer of the halides but I think you could do the same with a few high watt LED's added to the t5 setup. As far as heat I'm not sure. I know my t5's put out more heat than what I was led to believe by advertising but I think getting air movement is the key. I have heard that if you keep them good and cool they will easily last 18 months. It would take about 6 39 watt t5's to get where my 2-150 watt halides are. that's only a saving of 60 watts. about 150 dollars for replacing the mh or about 150 dollars to replace 6 t5's. I don't see a lot of savings other than in the longer bulb life. The big advantage of the t5's as Norman said is the array of spectrums you can put together. Lots of different k's. To each his own, they both have ups and downs. If a few dollars a month savings on electricity is a concern, maybe this is the wrong hobby....lol. When I do my 135 I do beleive I will go with a mix of halides and t5's though. But then again, I'm new and learning.
There is a big heat difference. The watts are the same, BUT the heat from the T5 bulb is spread out over a much greater area then the MH, which is a very concentrated source of heat, which makes it a more penetrating heat as far as heating up the water, and add a reflector like a luminarc or brite and you really increase the heat issue. I had to run a chiller on my 240 up north with 3 250w MH with luminarc reflectors and my canopy is opentop. I have a T5, 8 bulb 4ft. hood along with a 250 mini pendent now and don't need a chiller and that is with being down south with the humidity and heat. There has been some articles written on it on reef central, I can't seem to get them to come up, but I think most all agree T5's create less of a heat issue. I think they have a depth limit as far as growing acro's of say 24" roughly though and they don't shimmer the water as much as MH's.
MH's are the way to go with a shallow frag tank for very quick growth; however, when I had my 240, my halides would give me a par reading of like...500 at water surface and about 30-40 at the bottom of the tank. My VHO's (t-12's) gave me 125+ on the bottom of the tank and i believe 220+ on the surface. As said before energy consumption and temp are also a major concern.
And for anyone who has not had the pleasure of seeing fisherman's tank with the t5's....wow! You will be so focused on the beauty and colors you won't even notice the shimmer isn't there. For the first 5 minutes I didn't even realize he was running t5's. Anyone who says you can't get good growth out of t5's, go see his tank. He has an absolutely beautiful tank and I aspire to be that good some day.
so you dont think by the time you pack 8 T5's over a tank the heat isnt equal to MH's? Not arguing just asking...
Fisherman would be the one to give a definite answer through experience. But what he says makes sense. MH is more of a pinpoint heat source and it seems heat would sink into your water more from this. The t5's are spread over more of an area making heat transfer to the water less. I think with any setup a couple cheap fans from walmart placed on the back of the tank blowing over the water will do a fairly good job of keeping heat from sinking in. Maybe more evaporation but homeade RO/DI water is cheaper than a chiller.
Glad you liked the tank Jason-thankyou for the kind compliments. You are right on about the pin point source of heat. I'm no whatever expert you would call for here, so I can't talk in formulas and such, but if you take and concentrate a source of heat, it well penetrate a surface alot more then if the same amount of heat is spread out. As for heating up a given volume of area under say a closed canopy, I agree that the same amount of watts should be the same as for heating up that volume of air, but when the heat source is concentrated and it starts heating the water or the reflector with a concentrated source that in turn heats the area more also, and I think we can all agree that pentrating heat into the water is going to compound the rate of the tank heating up. I guess try wiping the reflectors on a T5 light hood, I wipe all mine off every week and even touch the bulbs with a damp cloth and try doing that to a MH light, you most likely well get burned and well most likely break the bulb. A Mh has a very small filament making the same amount of watts that a T5 spreads out the length of the tube.
Don't know if it adds anything... but I am about to get a RSM 250, it uses six (6) 39w T'5s for a total of 234 watts - I have seen lots of fantastic pictures of really nice coral growth in the RSM 250's, lots of the higher light requirement corals too (sps), in dozens and dozens of RSM 250 members tanks running the T5's.
