mh vs t5's

Discussion in 'Lighting' started by Travis1, 27 May 2009.

  1. Travis1

    Travis1 (wilsontravy)

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    i would jst like to know, what is the difference between lets say t5's and mh's regarding heat transferr? i am really confused in which direction to go, i have a 4 foot tank(standard with overflow). i no most probably the mh's will have more heat being generated off, but whats the difference between 8 t5's and 2 mh's? im trying to do away with a chiller at the moment. :whistling:
     
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  3. Fishy Steve

    Fishy Steve Hiden super user

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    Numerous people have said before that t5's give off the same amount of heat per watt as Mh's but it is spread out more evenly. Dunno if i believe it though. I have 126watts of t5's and get very little heat transfer but if i had one 150watt Mh above my tank i think i would see a substantial temp rise.
     
  4. Fishy Steve

    Fishy Steve Hiden super user

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    Replacing 8 good t5 tubes is gonna work out way more than 2 Mh bulbs i think. So either way is gonna cost in its own way. So maybe the cost of the chiller will b overtaken by the cost of the light replacing. As i dont own Mh's or a chiller can someone with more knowledge verify this as i dont actually have any figures.
     
  5. Travis1

    Travis1 Thread Starter (wilsontravy)

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    well most prob will be pu the mh's in. will just have to invest in a chiller. i think its the best option
     
  6. lanzo

    lanzo Sponsor

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    ill always go for MH
    it gives a nicer effect than the t5's, ut the heat it gives off is quite alot, but if you have a open canopy the heat wont be hectic
     
  7. Travis1

    Travis1 Thread Starter (wilsontravy)

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    i have a closed canopy, thats the problem. well will just have to test it. but true 8 t5's will definately xost more than 2 mh's.
     
  8. inflames

    inflames

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    Personally I think that the MH's will give off more heat than T5's. i have a 4 foot and also have a closed top canopy and even with just the T5's I have over heating problems. You could always add a few computer fans to draw the heat away in the canopy if possible(which I have done and it does help). In the long run the T5's will end up costing you more to replace. I was considering a chiller...now its winter so will wait for summer (gives me time to save!!!)
     
  9. lanzo

    lanzo Sponsor

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    x2 150w mh R1200 =R2400

    x8 t5's 39w R149 =R1192
    x4 ballast =R200 =R800
    x16 normal encaps =R240
    =R2232


    i think t5's will work out cheaper, but for R200 more ill go for mh

    my 1.2m i run x2 150w mh without a chiller, also a closed canopy
     
  10. DragonReef

    DragonReef

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    In Laymens terms... I can touch a T5 tube with by bare hand and at worst it's warm to the touch. If I keep my arm under the MH's for a few minutes while adjusting something in my tank, I can feel the sunburn effect afterwards.
    Yip I'd say Halides cook your tank.
     
  11. Travis1

    Travis1 Thread Starter (wilsontravy)

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    and you dont have a problem with tempreture? but its colder were you stay, i live in durban, high humidity here, thats the problem.
     
  12. Travis1

    Travis1 Thread Starter (wilsontravy)

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    and how far above the water is ur mh's lanzo?
     
  13. brettb2020

    brettb2020

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    dragon i cant touch my T5's for than a second. they damn hot!

    lets take an example like this, one 150w MH and 150w worth of T5. the same power. most of the power of MH and T5 bulbs get transferred to light and rest gets transfered to heat. and remember the wattaage is just how much electricity it uses, NOT how much light is given off, that lumens

    so electrical energy converted to light and heat.

    now a T5 bulb, depending on make, produces about 60-90 lumens per watt. a MH bulb produces 120 lumens per watt. so by those figures T5's create less light and more heat than MH for the same amount of wattage.

    BUT MH bulbs have more radiant heat. you can feel this if you put your hand near a MH bulb, you can feel heat almost a metre away. like a fire for example, you get the heat waves rising of the top and the radiant heat radiating outwards around the whole fire. radiant heat penetrates glass easily heating your tank.

    hope it makes sence :)

    my 2c
     
  14. brettb2020

    brettb2020

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    oh and just by the way wilson. there is a chiller in the classifieds! a very nice one and less than half of market price.
     
  15. Tony

    Tony

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    There's a good article on reefkeeping.com about the heat of lights. Just dig it out. Watt for Watt they give off the same heat. T5's don't penetrate as deep as halides, don't last as long, six months for T5's versus up to a year fot halides.
     
  16. Travis1

    Travis1 Thread Starter (wilsontravy)

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    thanks brett, saw that already, but thats only for 200 litres. looking for one a little bigger so that wen i upgrade i can keep it for the new tank.
     
  17. Travis1

    Travis1 Thread Starter (wilsontravy)

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    thanks tony. will look for it now.:slayer:
     
  18. lanzo

    lanzo Sponsor

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    one day in 3 years were temp got to 33C

    ut rest of the time 26

    my mh are very close to the water,:p
     
  19. silver phanton

    silver phanton

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    x2 150w mh R1200 =R2400

    x8 t5's 39w R149 =R1192
    x4 ballast =R200 =R800
    x16 normal encaps =R240
    =R2232


    now what is the cost of electricty for the 2 diffrent options? and I dont think its as simple as option 1 watts - option 2 watts. I think we still need to take into account voltage and amps
     
  20. brettb2020

    brettb2020

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    doesnt work like that. we are charged for electricity in kilowatt hours. so if we use an item that draws 1 kilowatt for one our, thats 1 kilowatt hour. we get charged 42c PLUS vat! voltage stays constant and current is directly proportional to the power.

    the equation is: power = voltage x current

    so the power usage is about the same.
     
  21. jacquesb

    jacquesb Retired Moderator

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    GEEZ BRETTB! That's BLOODY cheap!

    My electricity (even though it IS pre-paid) works out to 66 cents per kilowatt-hour! GEEZ!
     
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