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Re: [APD] Help With My New Tank!! -- or - Final Lighting Questions


After reading and rereading everyone's responses, I
have decided to attempt to implement MH cheaply :)

Good choice. MH is my favorite :-)

My only concerns are that I have but 5 inches from the
water to mount these lights...

Make sure you put a splash shield between the water and the lights. A piece of glass works well, tempered glass is best since it's stronger and less likely to break into knife-edged wedges. You'll need to make sure you use a fixture that can light a decent-size area from only a short distance away, which will probably mean you need to use horizontal (instead of pendent) style reflectors.

I figured that I could use a bunch of fans to push the
air out the open back of the canopy.  Sound okay?

Should work. You can even get fixtures that are set up to use in- and out-ducts to allow air to be circulated through the fixture itself. Fixtures like that are usually sold for hydroponics use. Remember that if you blow the fans across the water surface you will increase evaporation from the tank. Best is to rig your fixtures so that most, if not all, of the airflow is directed across the lights themselves.

You probably don't need a 'bunch of fans' -- one per light is most likely going to be sufficient provided they blow enough air. Pick some decent muffin fans of maybe 40-60 CFM or so for a 175w light and you should be fine. Make sure to pick *quiet* fans (low dB rating) or you're likely to be annoyed with the whine they make.

Also, I found that my tank is actually 60inches long
and 24" deep.  Since the lights must be mounted so
low.  Would it be better to use 3 lower watt lights or
would 2 175watt lights still be okay.

The standard MH bulbs are 175w, 250w, 400w, and 1000w. There are also 1500w and 70 watt bulbs (I have even seen 35 watters), but they aren't as common. In your application, 175 watt bulbs are probably perfect. Since you said in earlier postings that you wanted some shadow effects, the larger spacing is likely to create exactly the effect you are looking for. And you can always add another light later...

Finally, is there a place where i can get really cheap
ballasts.  Locally prices are outrageous.

Yes, try a local electrical supply house. Both Magnetek and Advance Transformer make MH ballasts that are sold for warehouse and outdoor lighting and are often used in aquarium ballasts (electrically aquarium MH setups are the same as commercial MH lighting). Advance has a nice kit that includes the ballast, an "ignitor" (really a capacitor, but you need it to start the arc in the bulb), a mounting bracket for the ballast, and some screws and wire fasteners. I was able to get the kits locally for somewhere around $30-35 each. You need an enclosure for the ballasts, which should be VENTILATED and METAL. Lots of surplus places have suitable enclosures. There are several posts from me in the archives dealing with the subject of DIY MH lighting and I list sources for all the big parts. My own setup uses a nice ventilated aluminum enclosure that originally held an "in-flight phone" from a system used in passenger aircraft. It was about $20 and easily holds three 175 watt MH ballasts. One of these days I should probably write an article about it and post some pictures...

Note that you should really use 105°C rated wire (common hardware store stuff is only rated for 75°C or 90°C). A good water and sunlight resistant wire type to use is type SJE. I have had good luck myself with Coleman Cable's "Seoprene 105" cable which is perfect for this application and is available in black (many other manufacturers now sell this type of cable in a bright yellow color which is obtrusive in an aquarium setup). You can probably order it or something similar from the same supply house you get the ballasts from. When I got the wire, I had to order a 250 foot reel (minimum stock put-up from the manufacturer), but many supply houses can cut shorter lengths.


Thanks again!!!


Waveform Technology
UNIX Systems Administrator

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