Lighting Confusion

[andysgirl8800]

Alright, so I have my MH and VHO lights installed over my tank, but was reading about some heat transfer issues. I have some questions about their installation and use:

How far off the water should the lights sit?
Should I use a glass/plexiglass shield between the tank and lights?
Will plexiglass or PVC tubes melt if too close to the lighting fixture?
How long should the lights be left on?
How many fans should I install into my closed canopy?

Thanks for your advice, as always!!

 

[HeavyHittah]

1: i think mh are supposed to sit somewhere between 6 and 9 inches from the water. and T5 can be between 3 and 5 inches.
2: I dont know
3: i know mh's can get hot enough to slowly melt the middle plastic support on tanks, so im guessing yes. but if you put the pvc tubes on the sides to hold up the t5's i dont think there would be a problem.
4: i say either have them come on around the time you wake up and whenever you go to sleep have them turn off. or you can just put them on an 8 hour schedule.
5: i say no less then two

hope i helped

 

[dustin_P74]

+1 heavy with a few corrections, for question 2. its your decision, i have seen it done both ways. and most people run their VHO's for about 12 hours and there halides for about 4-5 hours

 

[Bifferwine]

MH could heat your water, so I'd say to start them off 12" from the top of the tank, and move them up or down as your water temp dictates. If you have good ventilation in the canopy, it may not even be a problem, but it is easy to accidentally boil a tank with new lights (when I got my brand new MH on my 240, on the first day I accidentally got the tank to 95 degrees and killed 95% of my corals).

I would not use any lids on the tank, if that's what you mean. With MH, you should run the tank open air to better disperse heat (lids will cause your water to heat up more and cut down on oxygenation). The light itself should have a glass shield built in to protect the bulbs.

I don't know about melting, but MH can definitely damage plastic things. Keep them as far away as you can (I have two plastic fans clamped to the back of my tank to cool the water, and they have not melted yet under the lights).

If you only have fish (and no corals) at first, you only need to leave the lights on while you're home to look at the tank. Less light = less algae. So, for 4 to 6 hours for example. Once you get corals, you can up that. Most people leave their lights on for 8 to 12 hours a day (I do 9). Lots of people use timers to turn the actinics on before and off after the MH to give a sunrise and sunset effect. I.E. actinics on at 8 am, MH on at 9 am, MH off at 7 pm, actinics off at 8 pm.

And at least two fans. Most people have air being sucked in one end and being blown out the other. The more circulation, the better.