par meter findings

[Boret]

You probably have already read these articles but if you are looking into reflectors I think they are totally worth a reading:

 

Article 1

 

Article 2

 

This graphic is pretty clear on the overall advantage of a Diamond shaped reflector (i.e Lumenarc) at a depth of 12", combining all the PAR readings over 3x3, 2x2 and 1x1 areas. :

 

Edited August 29, 2009 by Boret

[davelin315]

Rob, you need to take into account the water agitation at the surface as well as the angle that you are measuring it at - a reading directly below a bulb will be different than a reading offset by a few inches as will be one that is at the edge of the reflector. You also should list not only the bulb brand, wattage, and color, but also the type of ballast firing the bulb as all of these (and the reflector) will influence the light output as far as PAR is concerned.

[Boret]

Rob, you need to take into account the water agitation at the surface as well as the angle that you are measuring it at - a reading directly below a bulb will be different than a reading offset by a few inches as will be one that is at the edge of the reflector. You also should list not only the bulb brand, wattage, and color, but also the type of ballast firing the bulb as all of these (and the reflector) will influence the light output as far as PAR is concerned.

 

Yeah!! if you are going to do it, do it right darn it!

[zygote2k]

There are so many variables to take into account- I just did the quick and easy measurement of light output coming from a given light fixture. In order to do a precise experiment, I would need lots of time. Maybe the next person that uses the meter can do it.

I did check 3 different bulbs in my malfunctioning 400w fixture- 10k Coralvue, 14k Coralvue, 14k Reeflux. All 3 bulbs emitted the same amount of light +/- 5% difference. All of the tanks that I tested, I tried to place the meter directly under the center of the bulbs to get the most direct PAR value.

[zygote2k]

I found out why my '400w' ballast wasn't working correctly- I opened it up to discover that it really is a 175w ballast. PAR readings with the new ballast:

 

At lens 2k+

1" above surface 950

1" below surface 650

middle 350

bottom 200

 

Now I wonder how my corals will be affected.....

[amos]

I found out why my '400w' ballast wasn't working correctly- I opened it up to discover that it really is a 175w ballast. PAR readings with the new ballast:

 

At lens 2k+

1" above surface 950

1" below surface 650

middle 350

bottom 200

 

Now I wonder how my corals will be affected.....

 

Rob,

 

That's an unpleasant surprise, but at least now you know what's going on with the system. You may want to be cautious of shocking your corals with a sudden intensity change.

 

thanks again for stopping by and taking the readings!

 

Jon

[Origami]

I found out why my '400w' ballast wasn't working correctly- I opened it up to discover that it really is a 175w ballast. PAR readings with the new ballast:

 

At lens 2k+

1" above surface 950

1" below surface 650

middle 350

bottom 200

 

Now I wonder how my corals will be affected.....

 

Rob, put some egg crate over the tank and a couple of layers of window screen to cut back on the light in the tank. Pull one sheet of window screen off per week and then remove the egg crate at the end. What temperature bulb were you running before? Chances are it was running way over to the yellow end of the spectrum if it was being underpowered.

[davelin315]

I found out why my '400w' ballast wasn't working correctly- I opened it up to discover that it really is a 175w ballast. PAR readings with the new ballast:

 

At lens 2k+

1" above surface 950

1" below surface 650

middle 350

bottom 200

 

Now I wonder how my corals will be affected.....

What brand of bulb was it? I have to confess I don't know an awful lot of how they fire, but I'm surprised it did at all and stayed lit, I wonder if it did any damage to the bulb? I would also screen your tank for a bit as the intensity has increased quite a bit - you don't want to burn your corals. Think of it as a cave dweller who suddenly is stranded in the desert without any shade.

 

Here's the stats I pulled from my tank build thread (page 10).

 

Took some PAR measurements on the lighting. With the exception of the bulb itself, the measurements are taken at the edge of the reflector in order to present the meter with a direct vertical path. These measurements were taken about 6" from the next edge of the next reflector.

• Above surface measurements
  
• 0-7" directly below bulb - 2000+
  
• All measurements are now at the side of the reflector
  
• 0 above water - 510 (8" below light at the edge of the reflector)
  
• 0 below water - 420 (8" below light at edge of the reflector, covered less than 1cm of water
  
• All measurements below are inches below water surface, edge of reflector
  1. 465
     
  2. 480
     
  3. 460
     
  4. 460
     
  5. 450
     
  6. 430
     
  7. 420
     
  8. 460
     
  9. 415
     
  10. 420
      
  11. 430
      
  12. 440
      
  13. 420
      
  14. 430
      
  15. 390
      
  16. 400
      
  17. 430
      
  18. 420
      
  19. 420
      
  20. 420
      
  21. 390
      
  22. 390
      
  23. 365
      
  24. 350
      
  25. 360
      
  26. 320
      
  27. 320
      

It's interesting to note that the PAR fluctuates as you go down in depth due to the angle that the light is coming in. These measurements were taken with the flow on and lots of surface agitation and plenty of current in the tank refracting the light. All measurements were the middle ground and have a +/- of about 10.

 

This does not take into account the types of bulbs and ballasts, but in case you were wondering, they are 3 day old bulbs, 20,000K Helios SE run on 400W PFO HQI ballasts - also run for 3 days. Total hours are less than 24 hours of use. Also, I imagine that if I were to turn the current off, it would increase the penetration. Another factor would be position at the edge versus directly below the meter. Lots of factors come into play, but these bulbs have a TON of output and excellent intensity. Keep in mind, this is also with no rock in the tank yet, so I imagine that this would have some sort of effect on the PAR.

[JMsAquarium]

A big thank you to Rob (zygote2k ) for returning the PAR meter today with a brand new battery.

[zygote2k]

another oldie with lots of info on antique lighting fixtures....

[gws3]

Reflectors definitely make a massive differece. I ran an aquaspacelight 2x250 when I first set up my 90 years ago. I couldn' get any par output over 300 near the top. When I went to lumenmax elites PAR is around 800 near the top. Oddly, once the corals adjusted, the colors weren't any diferent. But I did get alot more light on the bottom to support denser growth.

 

For anyone running nice MH bulbs in old reflectors... upgrade! you are throwing money out the window.

[STEVE]

What reflectors are you running now Graham?

[gws3]

Still with the lumenmax elites on the 90 gallon. I have a lumenbright mini on a 40 breeder and a lumenbright large on a 70 cube. I really like the lumenbright large stealth for the price.

 

When I finally upgrade to a large tank, I will do lumenmax elites or large lumenbrights. The lumenmax elites have more spread so they would be better if they are close to the water surface. The lumenbright are more focused, they'd be better 18-24" off the surface.

[STEVE]

I have 3 brand new (out of the box) Lumenmax elites that I just purchased that I was very disappointed with the spread of light. Was too "spotty" I thought. The par on them is CRAZY though. 1" below the surface was 1100, and on the sandbed it was 320, on the main reef it was around 650! That was mounted at 16" above the waterline. This was with my 300dd 27" tall tank.

[basser9]

You cant have it all either you get low par high spread or high par low spread.

Put 2 of the Lumenmaxs on a light mover and run a T5/LED OR SOME KIND OF STRIP

OF LIGHT ALONG THE WHOLE TANK a great option for a 300dd.