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How high wattage MH before heat problems


theclearblue

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theclearblue

Looking for anyone's practical experience with metal halide and heat. My 20 long tank just reached 5 weeks since it was set up (moved it from a 10 gallon I started to cycle). This past weekend I added a pair of false percs, and am planning to purchase and install a lighting system this week. I did my best at a DIY hood with the following tools: hammer, and a screwdriver. I had Home Depot measure and cut the boards (actually turned out to be pretty accurate cuts).

 

Attached are some pictures of my setup with the DIY hood above a LOA 65w and old 10 gallon Hood with 2x20w PC (threw those in for a few minutes to add some light to the pictures I was taking).

 

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As you can see, I left the hood without a back and only a bar across the top supported by L-Brackets on the inside and nails on top. I placed a 50lb bag of sand on it for two days, so there aren't any concerns about it holding the weight of a pendant. I figured this setup would allow heat to escape through the top and back.

 

I originally planned on adding a 70w MH but I figured I met as well spend the extra bucks to do it right if heat isn't a problem. Drilling a hole in the side for a fan is an option, but all I have is a dremel to do this, which would be a PITA. I'd really like to do it with a PFO pendant, and using ballpark figures, I expect the bottom of the pendant to be 9 inches above the surface of the water.

 

If I keep the temperature of the room low (~60), how high wattage could I go without running into heat problems? Is 250 watts a possibility? The cost from going 150 HQI to 250 really is negligible.

 

Thanks for any advice

 

[The 10 gallon you see underneath will evenutally become a sump/refugium, and I have no idea why there is a smiley face with its' tongue sticking out - oops]

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Hit up Home Depot! If I was in your position, I would do the 500w Halogen Regent pendant (look in DIY) and turn it into a 150 DE MH set-up, mounting the pendnant to the front part of the hood and pointing it down. Then I'd grab a cheap electronic ballast, flourescent end caps, and order a coralife 24" Acintic and mount it going along the top cross-bar. Get some polished metal edging (I think it's called edging) and make a reflector for the acintic bulb. The cost at Home Depot would be around $40-50. You'd have to order the MH ballast, bulb, and acintic tube light. We're looking at about $175-200 for the whole she-bang (maybe cheaper if you use eBay). HTH!

 

-Justin

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i have a 175w mh on my 20 h and have never run into problems with heat ing infact the temp drops if i turn off my heater so i would recommend getting a good reflector and getting one you will not regret it. sorry fpr not mentioning it earlyer but my ambient room temp is at 72 so you might be able to go with a 250 if you choose and my mh is only 4'' away from the water surface

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theclearblue

Hmm... well there's only about 3.5 inches of clearance in the front gap, so I'd have to take off the top cross bar and scoot it back a few inches. The hood itself is only 12 inches widec 15 high, and 30 inches long, would all of that fit in terms of width?

 

Just in case anyone was wondering, I went to all this trouble because hanging a pendant from the ceiling isn't an option.

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theclearblue

How about this fan blowing air against the wall and into the hood, it creates a fair amount of air flow through the hood. This is all I have to work with without going out and buying something.

 

DSCN0180-small.JPG

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When you want to go for regent way, 70w is OK. But 150w will be tricky. Bear in mind that 150W DE bulb is about a inch longer than 70W bulb.

Heat won't be a real problem as long as you leave tank top open or have a fan to blow air out.

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theclearblue

One of the reasons I steered away from the regent hanging below the cross bar was that they seem to take up a lot of room in height, effectively decreasing the space between the bulb and water surface. I really like the clean look/simple wiring/short height of the PFO though.

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Other pendent are at least a inch higher and a few inches bigger than regent pendant.

I think your hood is high enough to hold MH pendant. That will leave you about a few inch from the water surface, and thats ok unless you want MH pendent a foot over your tank.

Or you can tak out the cross bar at the middle of the hood, install two cross bar at the end of the hood, let sit MH pendent on them. You may use those cross bars to mound your PC lamps or moon light. That could be an idea, I guess.

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theclearblue

Do you think the pendant laying on two wooden crossbars would be a fire hazard? I really don't know how much heat these generate.

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Actually I have my 150w over two cross bar... for temporary setup. They are just plain pieces of pine from HD.

Heat generated from MH made the bar little brown, where the pendant contact the wood. But it is not gonna set a fire. That I am sure.

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theclearblue

Well I decided I'd go with a 250w HQI with a coralvue 20K bulb. I got an awesome deal on a new style 250w IceCap from a friend that he didn't need, the pendant and bulb should be arriving tomorrow, so hopefully it'll all be set up by tomorrow afternoon.

 

If heat becomes a problem I'll go with an open air bar across - a la glazer style.

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I've got a 175w mH and 110 watts of pc on my 20l with a mostly closed hood (venting on the sides and the small slits in the hellolights reflectors). A single computer fan keeps my temps hangin on the heater (78deg) with room temps from 70 to 75 degrees. without the fan I'll hit 84 a few hours after lites on. I don't think you'll have trouble with 250w in a 60deg room

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