DIY Metal Halide

[arvin]

Hi all,

I am planning to do a diy MH system. I already have a canopy and need your help in assembling the necessary pieces to build the MH system. I am a complete newbie and going to start from the scratch.

Here are some starter questions:

1) The tank is a 72g bowfront and depth is around 20 inches. I have a glass cover on top. There is six inches high opening on the canopy. So the MH will be about 7 to 8 inches away from the water with glass in between. Is this height good enough to minimize heat issues?

2) I am thinking of going with two 150W MH & two PC day lights & two PC acitinic lights. Is 150W good enough output for this tank or should I go for 175w or more?

3) If I can get some good deals on used MH light systems, will it be easier to dismantle the individual components and use it in my system? I am using a PC light system currently. Can I take it apart and move the light components to the canopy? Does it make sense to do this way or should I look for individual components and assemble it in the Canopy?

Thanks in Advance.

 

[DaveK]

I don't think you'll have any problems with the distance from the glass to the lighting.

150w bulbs tend to be double ended bulbs. These run extremely hot. I don't think I'd trust then in a wood fixture, since they could burn that. Use a metal fixture for double ended bulbs. They also require UV blocking glass to prevent you from burning the corals.

150w and 175w bulbs give about the same light, but the 175w bulbs tend to be mogul base. If you really want to ge more light, go with 250w bulbs, but be prepared to need to invest in a chiller.

I don't think you need the additional PC daylights. I'd use either just two actinice, or if you already have the PCs, make them all actinic.

I don't see any reason that would prevent you from using components from your existing lighting system. You might have to drill out a few pop rivets, but that's about all. Do check the condition, and replace parts that are damaged in any way.

If you get a really good deal on used stuff ok, but consider that with MH the cost is in the ballast. If the ballasts are coil and core ballasts, you might be better off just getting new electronic ballasts. Even thought they are $100 each, they will pay for themselves in a couple of years, with the energy savings.

Looks like a good project. Good luck!

 

[DaveK]

One other thought, make sure all the wiring you do inside the fixture is done with hight temperature rated wire. You can often find this for cheep at an auto parts store.

 

[arvin]

Thanks for the pointers Dave.

After doing some more reading on the subject, I am thinking of raising the height of the bulbs from the water to about 10".

Also should I close the front (with a door) and back of the canopy so that light does not seep or should I leave it open so it doesnt heat up? Image of the canopy is attached.

 

[DaveK]

I'd say closing in the front and back is a matter of personal preference. As long as the light isn't in your eyes when you are trying to view the tank, I'd say you were ok.

I might want to may sure the light only went into the tank, if I have young children around. I wouldn't want them staring into the light thinking it was "cool".

 

[arvin]

If I want to get new Icecap electronic ballasts, since I have two lamps,should I get two ballasts or can I use one ballast to hook up two lamps?

 

[DaveK]

With MH you usually need one ballast per lamp, no matter what ballast you use. (Note - there are a couple of exceptions, where it's a single box, but has two ballasts inside, but these are kind of rare.)