# Par reading on a zoomed 2x24 T5HO lights



## kevmo911 (Sep 24, 2010)

What are the reflectors like on those? And who is the bulb manufacturer? But that's very interesting, and - just like the Coralifes - surprisingly low.


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## Rockhoe14er (Jan 19, 2011)

bulb manufacturer is zoo med and in the zoo meds lights have a single reflector behind the lights.


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## redfishsc (Aug 29, 2010)

How old are the bulbs? 

Also, do they have any fans at all blowing on them, especially the end caps?



Rockhoe14er said:


> bulb manufacturer is zoo med and in the zoo meds lights have a single reflector behind the lights.



They should be giving 2 to 3X this amount of PAR. 


I think what is happening here is a combination of several factors. 


1) Bulb quality-- I don't know anything about Zoo Med other than they sell a lower cost T5HO bulb, so it's distinctly possible that they are a lower quality. I won't say they are because I don't know that for sure. 

2) Reflector quality-- a single reflector over 2 bulbs says that it's definitely not using the PAR that the bulb puts out--- much of it is lost to restrike. 

3) Bulb age *might* be an issue. If they are at a year old or more, it may be an issue but it's hard to tell since we don't know where Zoo Med's 12K and 5K start out. 

4) Bulb heat. If the fixture has no fans on them, the bulbs are probably not putting out sufficient light because of thermal issues. I always recommend a fan on a T5. 



That being said, I don't always follow what I recommend lol. I have a 4X24 T5 that has no fan on it and I am using 2 Zoo Med bulbs (I think they are Zoo Med, it's been a few months since I bought them lol).


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## macclellan (Dec 22, 2006)

redfishsc said:


> They should be giving 2 to 3X this amount of PAR.


What are you basing this statement on?


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## redfishsc (Aug 29, 2010)

What I've seen with my own eyes and tested with a PAR meter. 

The 4X24 that I have, when loaded up with new ATI bulbs, gave around 240 at 12". And the reflectors in my unit aren't even as good as TEK or ATI reflectors. Not even close. And I don't have active cooling; I expect the numbers to go up even more if I did actively cool my T5.

A two-bulb T5HO should be putting around 100-150 at 12" with properly designed reflectors. 


FWIW I've gotten about 280-300 micromols on a 6-bulb ATI Sunpower at 24" over a reef tank. They aren't overdriven, just well designed for good reflectors and cooling, and had slightly more expensive ATI and UVL brand bulbs that have been shown to be quite high in PAR output.


I think we terribly underestimate the quality difference between bulb manufacturers and reflector styles.


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## macclellan (Dec 22, 2006)

I agree that bulb and reflector quality make a huge difference (hence the gross oversimplification of WPG rules or Hoppy's charts). That sort of thinking needs laid to rest. 

You didn't specify which fixture in the first line. I assume not zoomed. It's not exactly a tek, which is why I don't find the low numbers surprising.

I tested my 4x54w catalina last night @ 24". Only pulled 72mms. One geisemann, one glo, one current, and I forget the fourth.


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## Dave-H (Jul 29, 2010)

macclellan said:


> I agree that bulb and reflector quality make a huge difference (hence the gross oversimplification of WPG rules or Hoppy's charts). That sort of thinking needs laid to rest.
> 
> You didn't specify which fixture in the first line. I assume not zoomed. It's not exactly a tek, which is why I don't find the low numbers surprising.
> 
> I tested my 4x54w catalina last night @ 24". Only pulled 72mms. One geisemann, one glo, one current, and I forget the fourth.


It's not really fair to lump the WPG rule of thumb and hoppy's charts together. The WPG rule is very old and based on assumptions that people have similar lighting setups, so it's mainly just obsolete. hoppy's charts were the results of a reasonable set of tests that he did on a small set of light setups, and he's been happy to knowledge that there is variation for reflectors/bulbs, etc. 

His simple chart is just that - a simple chart that shows how some different lights compared. There is lots of variation, but it's a big leap over WPG. I think if we were to collect enough data we'd see the ranges within the various types of lights and would be able to adjust accordingly.

Having tested quite a few setups now, one thing is certain. The variation in PAR between fixtures is dramatic. To date, I've observed that hands-down winner is LED as a category, and within the T5HO category the Catalina fixtures seem very, very good.

I am seeing variation amongst T5HO fixtures of about 75%.


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## houseofcards (Mar 21, 2009)

macclellan said:


> I agree that bulb and reflector quality make a huge difference (hence the gross oversimplification of WPG rules or Hoppy's charts). That sort of thinking needs laid to rest.
> 
> You didn't specify which fixture in the first line. I assume not zoomed. It's not exactly a tek, which is why I don't find the low numbers surprising..


I would have to agree. You simply can't put light intensity by fixture type into neatly designed boxes on a grid. When one T5HO fixture puts you in medium light and another high light it doesn't work for me, sorry. You would at least need some modifiers in there.


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## macclellan (Dec 22, 2006)

I didn't mean to belittle Hoppy's approach. It's much, much better than WPG, but not very helpful for T5s, IMHO.

It seems to me that the best approach is testing the most common fixtures and calling it a day, not trying to force that data onto a single curve. I think T5 fixtures vary by much more than 75%. Hoppy has two separate lines for AHS CFs versus the rest. In reality, there's everything between too. Same for T5s. Generalizing T5 PAR off of Tek fixtures overestimates the output of most T5 setups by quite a bit based on the PAR testing I've done.


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## Rockhoe14er (Jan 19, 2011)

The bulbs are only 6 months old.


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## Rockhoe14er (Jan 19, 2011)

anyone ever experience that a 5000k emits half the par of a 10,000k before? The bulbs have the same amount of usage which is why this is confusing to me.


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## zavikan (Jan 5, 2009)

Just to give a little info... I actually figured I would get approx the same PAR you got... before I even read your post.

My logic (basicly) using info from hoppy.

A t5ho bulb is approx 50 par at 21 inchs with a parabolic reflector.
When you look at a parabolic reflector behind a bulb, you see three bulbs total AND it basicly gives 300% output of light.
No reflector then should be 16.6 PAR

I have a two bulb zoomed unit as well. when I look at it at around 21 inchs, I see the two bulbs...and bits of bulbs in the reflector (not nice and focused like a parabolic).

So I added:
16.6 Bulb
16.6 Bulb
16.6 various improvement from pathetic reflector

Coooming up w/ 50 par at 21 inchs from a 2x39w zoomed unit!


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## Rockhoe14er (Jan 19, 2011)

The interesting thing i found was that like 30 par is from the 10,000 k at 21 inches and 13 is from the 5000k.


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