What to use as "hood" for DIY light?

Joshisdabest · 11-09-2012, 12:17 AM

What about just cutting a mirror and using adhesive silicone inside the gutter to create a reflector? You're angles wouldn't be perfect, but you can get them pretty close with this method. A long mirror like you hang on the back of the door wouldn't be any more than $15 or so even in Canada.

hobos · 11-09-2012, 12:37 AM

Don’t use silicone caulking to secure mirrored glass after a few weeks the silicone will start to react with the reflective coating on the glass marring it

Joshisdabest · 11-09-2012, 12:38 AM

It could mar slightly, but really not enough to worry about. You would only need a few dabs to take care of it.

**Hoppy** · 11-09-2012, 04:06 AM

Glass mirrors are poor reflectors. There is a big difference between a household mirror and a good reflector.

MrBrongher · 11-09-2012, 11:05 AM

Quote:

Originally Posted by Hoppy

Glass mirrors are poor reflectors. There is a big difference between a household mirror and a good reflector.

Explain, please. Is it something to do with the difference between visible light and photosynthetically useful light? I thought mirrors were, by definition, good reflectors.

**Hoppy** · 11-09-2012, 07:41 PM

Mirrors are accurate reflectors. You can see details very well when viewing a reflected image from a mirror, but that reflection may be made up of only 70% of the incident light. A polished aluminum reflector can reflect 95% or more of the incident light, but the image may be wavy or otherwise inaccurate. We want a reflector that redirects as much of the incident light as possible towards the tank, but we don't care at all whether the reflected image is accurate. Older mirrors can even reflect less than half of the incident light, as the silver coating on the back gets oxidized.

Diana · 11-10-2012, 02:36 AM

I have used gutter to make a cover for the bare light bulbs. It is not the right shape (parabolic) to make a good relector, no matter what treatment you do. I stuck 'peel and stick' mylar tape to some of them and spray painted the others with a silver paint.
At least they shade the light from entering the rest of the room, but I think more of it is absorbed by the gutter rather than getting redirected into the tank.

So... if you have overdone the lights, and simply want something so you are no blinded by the light that is sitting on top of the tanks, gutter is the way to go.

I got the stuff that is brown on the outside, and it looks better than the white, but I have not seen it lately.

Sotty · 11-10-2012, 10:04 AM

delete double post

Sotty · 11-10-2012, 10:15 AM

I'm not sure if you decided on a reflector yet. The ones from AH supply are very nice. I had 4 36 inch retrofit power compact kits over my 150 gallon. If you go this route, beware they edges are razor sharp. I cut myself fairly badly on one.

Sounds like you don't need to spend that kind of money on them since your tank isnt that deep, but thougt i'd throw in my 2 cents and say how pleased I was with mine.

dbl_dbl17 · 11-12-2012, 04:38 AM

Thanks for the heads up! Bulbs will be here Thursday. Is there any reason I should be concerned when it comes to the heat from the bulbs being close to the plastic? They won't be touching and I'm going to add vent slits but I'm still worried.

11-09-2012, 04:06 AM	#19
Hoppy Planted Tank Guru (View User Tanks) PTrader: (52/100%) Join Date: Dec 2005 Location: Sacramento, CA Posts: 17,199	Glass mirrors are poor reflectors. There is a big difference between a household mirror and a good reflector. __________________ Hoppy

11-09-2012, 07:41 PM	#21
Hoppy Planted Tank Guru (View User Tanks) PTrader: (52/100%) Join Date: Dec 2005 Location: Sacramento, CA Posts: 17,199	Mirrors are accurate reflectors. You can see details very well when viewing a reflected image from a mirror, but that reflection may be made up of only 70% of the incident light. A polished aluminum reflector can reflect 95% or more of the incident light, but the image may be wavy or otherwise inaccurate. We want a reflector that redirects as much of the incident light as possible towards the tank, but we don't care at all whether the reflected image is accurate. Older mirrors can even reflect less than half of the incident light, as the silver coating on the back gets oxidized. __________________ Hoppy

11-10-2012, 10:04 AM	#23
Sotty Planted Member (View User Tanks) PTrader: (0/0%) Join Date: Aug 2012 Location: Ann Arbor, MI USA Posts: 220	delete double post Last edited by Sotty; 11-10-2012 at 10:16 AM.. Reason: double post

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11-09-2012, 12:17 AM	#16
Joshisdabest Newbie (View User Tanks) PTrader: (0/0%) Join Date: Nov 2012 Location: Reading PA Posts: 3	What about just cutting a mirror and using adhesive silicone inside the gutter to create a reflector? You're angles wouldn't be perfect, but you can get them pretty close with this method. A long mirror like you hang on the back of the door wouldn't be any more than $15 or so even in Canada.

11-09-2012, 12:37 AM	#17
hobos Algae Grower (View User Tanks) PTrader: (0/0%) Join Date: Feb 2012 Location: Ottawa Canada Posts: 106	Don’t use silicone caulking to secure mirrored glass after a few weeks the silicone will start to react with the reflective coating on the glass marring it

11-09-2012, 12:38 AM	#18
Joshisdabest Newbie (View User Tanks) PTrader: (0/0%) Join Date: Nov 2012 Location: Reading PA Posts: 3	It could mar slightly, but really not enough to worry about. You would only need a few dabs to take care of it.

11-10-2012, 02:36 AM	#22
Diana Planted Tank Guru (View User Tanks) PTrader: (0/0%) Join Date: Jan 2010 Location: Contra Costa CA Posts: 5,012	I have used gutter to make a cover for the bare light bulbs. It is not the right shape (parabolic) to make a good relector, no matter what treatment you do. I stuck 'peel and stick' mylar tape to some of them and spray painted the others with a silver paint. At least they shade the light from entering the rest of the room, but I think more of it is absorbed by the gutter rather than getting redirected into the tank. So... if you have overdone the lights, and simply want something so you are no blinded by the light that is sitting on top of the tanks, gutter is the way to go. I got the stuff that is brown on the outside, and it looks better than the white, but I have not seen it lately.

11-10-2012, 10:15 AM	#24
Sotty Planted Member (View User Tanks) PTrader: (0/0%) Join Date: Aug 2012 Location: Ann Arbor, MI USA Posts: 220	I'm not sure if you decided on a reflector yet. The ones from AH supply are very nice. I had 4 36 inch retrofit power compact kits over my 150 gallon. If you go this route, beware they edges are razor sharp. I cut myself fairly badly on one. Sounds like you don't need to spend that kind of money on them since your tank isnt that deep, but thougt i'd throw in my 2 cents and say how pleased I was with mine.

11-12-2012, 04:38 AM	#25
dbl_dbl17 Algae Grower (View User Tanks) PTrader: (0/0%) Join Date: Feb 2012 Location: Ottawa, ON Posts: 60	Thanks for the heads up! Bulbs will be here Thursday. Is there any reason I should be concerned when it comes to the heat from the bulbs being close to the plastic? They won't be touching and I'm going to add vent slits but I'm still worried.