halide retrofit

[glinker97]

im going to build my own hood for my tank and was thinking of installing a 175 watt hailde and a 2 95 wat pc's in it. i am told that the halides generate a lot of heat. i was wondering if i installed a 3" fan would that dissapate the heat or is the sucker going to catch fire or some wierd thing like that?
thanks
greg:confused:

[Safir]

I think the fan is more to cool teh bulb and air in the hood than anything else, but my 175W MH retrofit kit came with a 3" fan, so i'm assuming it will be sufficient.

[Timothy01]

should make a thread with pics and keep us informed. what matirial are you gonna make your hood from

[Fast Fred]

You should be fine mounting the MH in the hood, provided the hood is not plastic. The MHs do generate a lot of heat, and the main problem with this is that it raises the water temp in the tank. The fan will help reduce this problem by a.) cooling the bulb, and b.) aiding in increased evepaoration, which aids in cooling the water.

My wooden hood has 3ea MHs in it with 4ea 4" fans. No problems so far.

[glinker97]

thanks for aleveating my fears. im just getting my tanks going. matter of fact havent bought the tank yet .but ive done my reasearch and know what i want. im building the stand today and then the hood and will get the tank next week. going to take my time and it it right for a change.
thanks folks

[KEITHMC]

<a href=showthread.php?s=&postid=7036748#post7036748 target=_blank>Originally posted</a> by glinker97
im going to build my own hood for my tank and was thinking of installing a 175 watt hailde and a 2 95 wat pc's in it. i am told that the halides generate a lot of heat. i was wondering if i installed a 3" fan would that dissapate the heat or is the sucker going to catch fire or some wierd thing like that?
thanks
greg:confused:

just remember when you mount a fan in a hood like this have the fan blow out of the hood and not in or you will push the heat from the mh to the water!

[Fast Fred]

I'd have to respectfully disagree with Keith. I had my fans blowing out from the hood, I switched them to blow cool air in across the bulbs, and I feel I have better cooling this way. Just be sure you have someplace for the warm air to escape. Also, by blowing air in, the fans will not corrode nearly as fast.

[Timothy01]

i agree with fast fred on this one as lonmg as you have a place for heat to escape you would want the fans blowing inward

[Phyxius]

I also agree with Fast Fred on the blowing in although they can be mounted both ways. I did mine blowing in on all 3 of my tanks. The canopies all have open backs so the air has a place to go. In blowing in they are mounted low enough they cause a cooling effect by blowing across the surface of the water as well as moving hot air out the back. Buddy has a tank pulling air out and has replaced his fans already due to corrosion from the salt vapor running through the fans......

[comatose]

i agree also let them blow in and install them as low as possible, i don't think you'll have to worry about that much heat that it will catch fire, but what you may want to do is put a small spacer between the the top of the hood and the MH shield, some MH kits come with spacers, I think mine were 1/4" spacers, it keeps the heat from transferring from the metal to the wood on the hood.

BTW, you said your building the hood and stand before you buy the tank, just make sure you build to the right dimensions of the tank, some tanks makers give dimensions of the inside and some give the outside dimensions and some are off a bit all together.

[zeblisik]

I've read that you shouldn't have the fans taking in cool air; that you should not have fans blow cool air onto metal halides in case they shatter.

Exhausting the hot air makes more sense to me.

[zeblisik]

http://www.reefkeeping.com/issues/2002-06/jg/index.php

Towards the bottom of the article under the "Additional Components" section.

I did not remember the reason correctly but there it is.

[comatose]

it doesn't say not to blow cool air in, it just says dont blow the cool air directly onto the bulb. which is correct, MH bulbs burn better hot.

thats why i mention put the fans low to blow over the water surface.

[dtaranath]

agreed with comatose. I have two 250's with 4" fans blowing in at the bottom of the hood on both sides. The back is partially open. This only raised my tank 1 or 2 degrees. the lights are about 9-10" off the water.

[glinker97]

I do belive i will compromise. one on one end blowing out, and the other blowing in. and mount them low woth spacers at the top between the reflector and the hood. yeah comatose i went to the lfs put the deposit down and mesured the tank. ;)

[dtaranath]

<a href=showthread.php?s=&postid=7047834#post7047834 target=_blank>Originally posted</a> by glinker97
I do belive i will compromise. one on one end blowing out, and the other blowing in. and mount them low woth spacers at the top between the reflector and the hood.

just keep in mind that if your fan blowing out craps out after 6 months, it may be because of salt creep.

[comatose]

<a href=showthread.php?s=&postid=7047834#post7047834 target=_blank>Originally posted</a> by glinker97
I do belive i will compromise. one on one end blowing out, and the other blowing in. and mount them low woth spacers at the top between the reflector and the hood. yeah comatose i went to the lfs put the deposit down and mesured the tank. ;)

ok i was just making sure you knew the size and just not relying on specs from a data sheet, saves a lot of trouble when you find out you built everything the wrong size, i myself have done it before, thank god i screw everything and was able to make adjustments.

[glinker97]

only reason i made sure comatose as i the same as you have done it before and it was nailed.noone ever said i was to bright