150w vs 250w

robby21 · 04/29/2006, 03:02 PM

Hello

do you guys think that a 150w hqi at 6 inch from the surface of the water equal a 250w at 12 inch from the surface?

robsmith32 · 04/29/2006, 06:33 PM

if look at sanjays page, it doesn't show diff in height from surface.
but there are some bulb/ballast at 150 that outperform other combos at 250w.

bertoni · 04/29/2006, 06:35 PM

That would depend also on the reflector. Sanjay's pages also have good reflector reviews.

robby21 · 04/30/2006, 06:09 AM

I mean if you use the same reflector and ballast of course

finrod2 · 04/30/2006, 08:59 AM

The inverse square law states that a light source twice the distance would need to be 4x the intensity to equal the original. At least thats what my astronomy books tell me.

bertoni · 04/30/2006, 09:10 AM

That only applies to a point source, unfocused. A foxuses beam won't lose much intensity while it remains coherent, the "near field" effect, I think it's called.

So it depends on which reflector is used. Some focus better than others. The same ballast won't work for the two separate bulbs.

jman77 · 04/30/2006, 11:28 AM

I have a dual 250w HQI fixture over my 58g. As soon as it's time to change the bulbs i'm switching the ballasts, bulbs, and sockets to a 150w setup with 10k bulbs and lower the fixture closer to the water.

The 250's are really strong and give off a lot of bloody heat for something that is going to run 8 hours a day. And HQIÃ¢â‚¬â„¢s use up more juice than what is statedÃ¢â‚¬Â¦. A 150w uses around 200w and a 250 uses around 300.

bertoni · 04/30/2006, 02:23 PM

The wattage rating for the bulb is for the bulb only. The ballast also wastes some energy as heat.

I'd be tempted to go with the Iwasaki 175 W bulbs in some ReefOptix or similar pendants. I have one over a 29g and like it a lot so far.

04/29/2006, 03:02 PM	#1
robby21 Registered Member Join Date: Mar 2004 Location: Far East Posts: 51	150w vs 250w Hello do you guys think that a 150w hqi at 6 inch from the surface of the water equal a 250w at 12 inch from the surface?

04/29/2006, 06:35 PM	#3
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	That would depend also on the reflector. Sanjay's pages also have good reflector reviews. __________________ Jonathan Bertoni

04/30/2006, 08:59 AM	#5
finrod2 Premium Member Join Date: Dec 2003 Location: Cary, IL Posts: 408	The inverse square law states that a light source twice the distance would need to be 4x the intensity to equal the original. At least thats what my astronomy books tell me. __________________ New 375G 84"x42"x27", ~100g sump/refugium, 4 x EcoTech Radion XR30G4 Pro + T5, Reef Dynamics XRC1000.5 skimmer, GEO 181 Calc Reactor Current Tank Info: 375G 84"x42"x27" SPS/Fish

04/30/2006, 09:10 AM	#6
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	That only applies to a point source, unfocused. A foxuses beam won't lose much intensity while it remains coherent, the "near field" effect, I think it's called. So it depends on which reflector is used. Some focus better than others. The same ballast won't work for the two separate bulbs. __________________ Jonathan Bertoni

04/30/2006, 02:23 PM	#8
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	The wattage rating for the bulb is for the bulb only. The ballast also wastes some energy as heat. I'd be tempted to go with the Iwasaki 175 W bulbs in some ReefOptix or similar pendants. I have one over a 29g and like it a lot so far. __________________ Jonathan Bertoni

04/29/2006, 06:33 PM	#2
robsmith32 Registered Member Join Date: Jun 2005 Location: BUford, ga Posts: 609	if look at sanjays page, it doesn't show diff in height from surface. but there are some bulb/ballast at 150 that outperform other combos at 250w.

04/30/2006, 06:09 AM	#4
robby21 Registered Member Join Date: Mar 2004 Location: Far East Posts: 51	I mean if you use the same reflector and ballast of course

04/30/2006, 11:28 AM	#7
jman77 Registered Member Join Date: Apr 2005 Location: West Palm Beach, Florida Posts: 2,391	I have a dual 250w HQI fixture over my 58g. As soon as it's time to change the bulbs i'm switching the ballasts, bulbs, and sockets to a 150w setup with 10k bulbs and lower the fixture closer to the water. The 250's are really strong and give off a lot of bloody heat for something that is going to run 8 hours a day. And HQIÃ¢â‚¬â„¢s use up more juice than what is statedÃ¢â‚¬Â¦. A 150w uses around 200w and a 250 uses around 300.