Fun with the PAR meter - T5, Metal Halide and PC numbers

[mojo]

Dakota;44929 wrote: I'm not sure if this is related to the thread or not, but I stumbled across some interesting information about DE metal halide bulbs and another reason why they have such high PAR.

The 150 DE actually draws about 214 watts.

The 250 DE actually draws around 330 watts.

Different bulbs seem to draw different amounts of power, and these results are from bulbs driven by magnetic ballasts. The electric ballasts seem to drive the bulbs much closer to the rating of the ballast.

If you are running a DE bulb on a magnetic ballast and have access to a Kill-O-Watt meter, test it out and see what it is actually drawing. It might be helpful to include it in with this testing if possible.

Looking at the PARs of the T-5s vs. DE halide setups of similar wattage made me remember this. Just thought I'd share.

Hmm- I have to disagree with the analysis here- a DE bulb is the same thing as an SE bulb without the outer shielding. A magnetic ballast will drive a 250w bulb to ~300 watts whether it's a DE or SE. The difference in output isn't a result of the bulb design itself, but because of the reflector design. A DE bulb can be placed much closer to the reflector material, and thus be reflected down more effectively, thus resulting in a higher PAR directly below the light, but not to the sides. Neither SE or DE is more efficient - they just allow the light to be reflected differently.

Also- an electronic ballast will drive at exactly the wattage stated - 250w bulb with 250w ballast will pull 250w, no matter what 250w bulb is put on there. I've tested it myself to be sure....

 

[mojo]

sammy33;44286 wrote: You can do a conversion from PPF (PAR) to LUX. Multiply any of the PAR values by 71 to find the LUX value.

How can you do this? If you have a really yellow bulb, the LUX (which includes all available light) will be much higher than the LUX put out by the same bulb in a blue variation, but the blue bulb's PAR will be higher....

I could see a conversion of x71 for 14k bulbs or something, but I don't see how you can make a blanket conversion, since they're measuring different things. That's like measuring the accelleration of a car by looking only at the engine size and not the torque/horsepower specs...

Do you have a reference?


Good work. I'll try to test my tank and add the results here.

 

[nishant3789]

this thread should some how be put into the arc wiki or somewhere where more people from all over the globe can add their readings. A really good data base would help people out alot with research, learning, etc. looking great sam, i added some rep for you too. I still really want to see what kind of par a 70 watt hqi would put out though!
Nishant

 

[sammy33]

mojo;50545 wrote: How can you do this? If you have a really yellow bulb, the LUX (which includes all available light) will be much higher than the LUX put out by the same bulb in a blue variation, but the blue bulb's PAR will be higher....

I could see a conversion of x71 for 14k bulbs or something, but I don't see how you can make a blanket conversion, since they're measuring different things. That's like measuring the accelleration of a car by looking only at the engine size and not the torque/horsepower specs...

Do you have a reference?


Good work. I'll try to test my tank and add the results here.

This conversion is based on what Apogee Instruments (the manufacturer of my PAR meter) suggests for readings conversions on their quantum meter. There are other factors for different light sources. A conversion factor is not given for different spectrums within a given light source.

http://www.apogeeinstruments.com/conv_lux.htm">http://www.apogeeinstruments.com/conv_lux.htm</a>

I gotta think that this is in the ballpark (a good average at least).

 

[mojo]

sammy33;50570 wrote: This conversion is based on what Apogee Instruments (the manufacturer of my PAR meter) suggests for readings conversions on their quantum meter. There are other factors for different light sources. A conversion factor is not given for different spectrums within a given light source.

http://www.apogeeinstruments.com/conv_lux.htm">http://www.apogeeinstruments.com/conv_lux.htm</a>

I gotta think that this is in the ballpark (a good average at least).[/QUOTE]

Thanks for the link. It appears that the factor does change depending on the color temp of the lights. I wonder if the 14K+ bulbs are even on this chart, given how blue they are compared to everything else. I have a lux meter, but my 1000w lights are off the scale. I'll try on a 250w when I get a chance...

 

[mojo]

Nishant3789;50554 wrote: this thread should some how be put into the arc wiki or somewhere where more people from all over the globe can add their readings. A really good data base would help people out alot with research, learning, etc. looking great sam, i added some rep for you too. I still really want to see what kind of par a 70 watt hqi would put out though!
Nishant

I agree 100%, and was thinking the same thing. Would you mind working on the wiki pages? I can get them setup and going if you're willing to add the info that Sammy and others provide. PM me.

 

[jessezm]

Sammy, when are you coming to Macon?

 

[dakota]

mojo;50543 wrote: Hmm- I have to disagree with the analysis here- a DE bulb is the same thing as an SE bulb without the outer shielding. A magnetic ballast will drive a 250w bulb to ~300 watts whether it's a DE or SE. The difference in output isn't a result of the bulb design itself, but because of the reflector design. A DE bulb can be placed much closer to the reflector material, and thus be reflected down more effectively, thus resulting in a higher PAR directly below the light, but not to the sides. Neither SE or DE is more efficient - they just allow the light to be reflected differently.

Also- an electronic ballast will drive at exactly the wattage stated - 250w bulb with 250w ballast will pull 250w, no matter what 250w bulb is put on there. I've tested it myself to be sure....

That is interesting. Thank you.
So a magnetic ballast will also overdrive a SE bulb. That makes perfect sense due to the operation of the ballast being the same for both types of bulbs.

That means the difference in light intensity between DE and SE bulbs BOTH running on magnetic ballasts is due to the greater efficiency of the DE reflectors. But factoring in the loss from the protective glass needed for the DE bulbs of around 15 - 20%, should make SE bulbs the better choice for lighting intensity.

I keep reading statements that say DE bulbs were designed to be driven by magnetic ballasts and electronic ballasts will underdrive them and shorten the bulb life. But, if I understand this right, the DE bulbs need the extra power of the magnetic ballast to overcome the loss of intensity from the protective glass. They should run fine on an electronic HQI ballast, but look dimmer.

Sammy, this is a great thread. I hate to keep hijacking it with my own personal questions, but I'm in the midst of trying to decide between a SE or DE lighting setup for my new tank.
Seeing the setup info. and the intensity info. has been very helpful.
Thank you very much!

 

[sammy33]

jessezm;50627 wrote: Sammy, when are you coming to Macon?

We will have to work out a time. I really need to come see your tank. :yes:

 

[justonemoretank]

Dakota;51463 wrote: the difference in light intensity between DE and SE bulbs BOTH running on magnetic ballasts is due to the greater efficiency of the DE reflectors. But factoring in the loss from the protective glass needed for the DE bulbs of around 15 - 20%, should make SE bulbs the better choice for lighting intensity... the DE bulbs need the extra power of the magnetic ballast to overcome the loss of intensity from the protective glass.

Two things... SE bulbs already have the glass UV filter incorporated into the bulb design while DE bulbs do not. The DE bulbs are therefore not 'fighting against an extra glass filter' as compared to the SE bulbs. You are correct however that better, more efficient reflectors can be designed with the DE bulbs over the SE bulbs.

 

[mojo]

Dakota;51463 wrote: So a magnetic ballast will also overdrive a SE bulb.

Or a DE bulb- remember, they're the same thing in different packages.

That means the difference in light intensity between DE and SE bulbs BOTH running on magnetic ballasts is due to the greater efficiency of the DE reflectors.

Correct.

But factoring in the loss from the protective glass needed for the DE bulbs of around 15 - 20%, should make SE bulbs the better choice for lighting intensity.

Not really- JustOneMoreTank hit the nail on the head - SE bulbs have the same glass protection, but it's already on the bulb.

I keep reading statements that say DE bulbs were designed to be driven by magnetic ballasts and electronic ballasts will underdrive them and shorten the bulb life.

DE and SE bulbs can run off of either ballast type (assuming you have the correct magnetic ballast for the type of bulb). An electronic ballast runs the bulbs at the proper wattage, can run any type of bulb, and are more efficient (in terms of energy wasted on the ballast itself). The tradeoff is that they are more expensive initially.

I'm in the midst of trying to decide between a SE or DE lighting setup for my new tank.

It comes down to this:

If you have depth, and want to minimize wattage required, use DE bulbs. You'll get more "punch" into the water from a single light source. However, you'll probably need one more because you won't have much spread (ie- if you need 3 SE bulbs, figure that you'll need 4 DE pendants. It's not that one is better than another, it's that they are useful for different scenarios.

I originally (and may soon again) had four 250w DE bulbs on my 26" deep 240g, and I was doing fine with that, for whatever it's worth.

 

[sammy33]

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My office tank - 7g Mini Bow with 70w DE Sunpod with Electronic ballast. The light is about 3"-4" off the water. The lamp is about 2 months old and the fixture/ballast is about 5 months. This is pretty good performance for only 70 watts!

 

[skriz]

You're more than welcome to come by my place and test my MH. I have both 250w and 400W. I also, just replaced some bulbs (i got them from you, so you already know that!). Would be a good way to test both wattages in one shot.

I am running 250w XM 10K, and 400W BLV 14k.

One XM is Old and the other is brand new.

 

[victor626nj]

wow i was there today as he was doing this and the camera does the tank no justice much more impressive in person

 

[jeep9783]

Ok this really upsets me i got the par meter today and measured my display 5in off the water 250de 20k 1week old with two 65w actinics-par at the halide its self 800, par at 5in under water 68 par at where clam is at bottow of a 33 cube 23....xm 20k the ballast is a no name chinese one but i have already placed the order for a ushio 250de 10k, ok now the frag tank (20gal) 150w de coral life driven by isb solo basic par under the light 1670, par at the very bottom of the tank 403, tank is only a 20h but that is bs...but on the bright side i did order the bulb but if anyone has a nice halide ballast for 250w please pm as i can tell i am in need.


Chris

 

[ouling]

Chris, let me get the par meter tomorrow. I'll show you guys what 2 400W EVC 10K running on PFO HQI ballast with Parabolic batwing reflectors will do.

 

[skriz]

Are the EVC's yellow in color? They're such par beasts!

 

[jeep9783]

I thought the the top of the line bulb was ushio and that they were the par beasts?

 

[ouling]

Depending on the application and the ballast. Best Par for a PFO Magnetic ballast that is in the 10K-21K range is the EVC 10K bulbs, hands down.

http://www.cnidarianreef.com/lamps.cfm">http://www.cnidarianreef.com/lamps.cfm</a>

This is how the EVC looks when its burned for 40 hours. It is absolutely blinding!
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[sammy33]

jeep9783;77321 wrote: Ok this really upsets me i got the par meter today and measured my display 5in off the water 250de 20k 1week old with two 65w actinics-par at the halide its self 800, par at 5in under water 68 par at where clam is at bottow of a 33 cube 23....xm 20k the ballast is a no name chinese one but i have already placed the order for a ushio 250de 10k, ok now the frag tank (20gal) 150w de coral life driven by isb solo basic par under the light 1670, par at the very bottom of the tank 403, tank is only a 20h but that is bs...but on the bright side i did order the bulb but if anyone has a nice halide ballast for 250w please pm as i can tell i am in need.

Chris

Chris - you may want to check your PAR again on your cube tank after you get the Ushio 10K lamp. I had a similar issue with a 150w XM 20K only producing about 205 PAR (at the surface). Switched to a Ushio 14K and now have over 800 PAR at the surface.