I currently have 2-250W MHs on my 120g (48x24x24) tank. I'm thinking about replacing with T5s to reduce heat and lower electricity usage. A MH light is generally considered to cover about 24" of tank length which is easy to do since the assemblies are relatively small. How many T5 lamps do you think it'll take to cover 48" if 24" lamps are turned "north-south" instead of using 48" lamps "east-west"?
Joe I have a 8 bulb 48" running E/W on 4' of my 240. My tank is 30" from F-B, I would think you would need atleast a 6 bulb. My 8 bulb hood is 19" wide with the 8 bulbs measuring 14" wide. Why not run a 48" E/W, the 48" is 54 watt verses the 24" is 24 watt, thats 30 watts per bulb. Also the 24" the most I can find is 6 bulb and most are 4 bulb and all seem to be around the $300 range and you can buy most of the 6 or 8 bulb 48" for $425 to $460 range. I really like my sunlight supply tek HO light, has a really good reflector. cheers
The wattage is relative based on the lamp length. As long as I'm covering the tank properly, the light output should be similar. However, I haven't researched cost differences completely yet. I will be using retro kits since I have a custom built canopy. (Chris' handiwork)
cost comparison is not going to help you much. 48"retro reflectors are around 25.00 each versus 21.00 for a 24 " you would need 4@48" 100.00 versus 6-8@24 inches 130.00-168.00 end caps and stand offs run about 12.00 per set so 48.00 versus 96.00(if you went 8 wide) bulbs i havent priced yet. ballast would be the same. you can run 16 ft of t5 bulbs off a workhorse 7 ballast and north side sells them for about 58.00 but i have found them much cheaper then that. i would expect you would want a bulb every 8 inches minimum so your looking at at least 6 sets of bulbs to upkeep versus 4 if you wanted to pack them in length ways. the only benefit i would see to doing it that way would be total tank light would be more even, but in reality we hardly ever place corals in the very back or front of our tanks so it would be overkill for the most part.
Yeh, I was just fixing lunch and realized you would have twice as many bulbs running N/S as E/W and would add up close to the same, 12x24=288 verses 6x54=324, tho running the 8x54=432 would be quite a bit more W. cheers
My opinion is that they ought to be spaced on 2" centers apart, that is what most all the premade hood ones are. The retro fit ones I've seen are each relector is for 2 bulbs, I guess you could space the reflectors further apart but every 2 bulbs well be 2" ctrs.
24" of tank at 2" apart would require 12x54W lamps? That's 648W which actually increases my electricity consumption over 2-250W MHs. What am I missing?
Joe as I stated above my tank is 30" front to back and I am running a 8 bulb which is what I think you would need but said you might could do a 6 which wouldn't be my choice. Like Jason says we don't usally place high light demanding stuff up front or way in the back, plus most reefs sit back from the front and slope upward. I am just saying what my T5 factory made hood has the lights spaced at 2" ctrs and the retro fit reflectors I have seen come in 2 per reflector and I would think that is what they well be at, not saying you can't space the reflectors out. Maybe to get the light intensative needed to grow light demanding corals you need them spaced a 2" and that many bulbs, maybe that is why people don't use VHO's for high light corals, can't get enough together, heck I don't know, just letting you know what the facory boys are doing. cheers
