PAR vs Distance, T5, T12, PC - New Chart - Page 11 - The Planted Tank Forum
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post #151 of 776 (permalink) Old 10-12-2010, 09:37 PM
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Wow, I just found this thread. According to the chart I'm at the medium to high light with just my one fixture.

I guess I need to raise the one up and remove the other one altogether.

Definitely worth a sticky!!
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post #152 of 776 (permalink) Old 10-13-2010, 03:40 AM
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An exceptional post, thanks Hoppy.
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post #153 of 776 (permalink) Old 10-13-2010, 04:00 AM
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Originally Posted by HouseofZoo View Post
Wow, I just found this thread. According to the chart I'm at the medium to high light with just my one fixture.

I guess I need to raise the one up and remove the other one altogether.

Definitely worth a sticky!!

That's another issue/question. What PAR difference is there between 2-4 individual reflector T5HOs, and a 2-4 bulb fixture without individual reflectors?

~Amanda~

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post #154 of 776 (permalink) Old 10-13-2010, 04:27 PM Thread Starter
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That's another issue/question. What PAR difference is there between 2-4 individual reflector T5HOs, and a 2-4 bulb fixture without individual reflectors?
The data I used came from both clip on single bulb reflector lights, and shaped single reflector for multiple bulbs lights. I couldn't see any significant differences in the PAR outputs. But, I'm sure there are differences. The charts only get you close to the desired PAR. You have to use a PAR meter to get an accurate measurement for your tank, fixture and installation. I'm not convinced that is necessary, but it might be desirable.

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post #155 of 776 (permalink) Old 10-13-2010, 04:40 PM
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Results of my PAR testing

Hey folks,

Just wanted to share the details of some recent PAR testing I did. I borrowed a PAR meter from my local club (Hoppy and Tom). I wanted to compare this to the light fixtures I had to see how reliable the information is, because we all know every fixture and light bulb is different. I think you'll see that PAR charts are meant to only be used as a rough guide. The only real way of knowing how much light you have is to test YOUR specific setup. There are way too many real world variables that will affect readings from one tank to the other.

Here's some important things you should know about my testing:
1. The Lowes and Current/Nova fixtures were tested on a standard 20g tank, with water. The sensor was placed in the middle of the tank, right under the fixture.

2. The Lowes & Current/Nova lights are 48" long, and the tank is only 24" long. To avoid having any stray light afftect the reading, I wrapped the overlapping section of the fixture with a towel. Removing the towels caused an increase of 4-5 micromols.

3. The Lowes fixture is black metal, even where the bulbs are. This is obviously isn't a good color for reflection, so I also wrapped the inside with aluminum foil and took more readings.

4. The Current/Nova fixture uses two bulbs, very close together. This has a very cheap thin aluminum reflector that goes over both bulbs.

5. The bulbs in the Lowes & Current/Nova fixture are fairly old, all over a year. Please keep this in mind as new bulbs may give a higher reading. The only bulbs that were brand new were the Giesemann bulbs in my Catalina fixture (3 days old at the time of testing).

6. I only took one reading with the Catalina fixture since it's mounted to a hanging bracket and the tank is heavily planted. I may try some more readings, but for the time being, it's just at 28". Also note that this is a 4-bulb fixture. I only tested 2 bulbs, in the outer most banks.

7. For the Current/Nova fixture, I had 3 types of bulbs. I took individual readings from each bulb and compared the results as seen below. Again, keep in mind that bulb age may be a factor. I did not go out and buy new bulbs to test this fixture.

Any questions please feel free to ask! I have a few more desktop lamps/fixtures that I will be testing in the days to come



~ Jose



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post #156 of 776 (permalink) Old 10-13-2010, 04:52 PM
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I'm about to order a 2 x T5HO fixture from Catalina and mount it about 28 inches off the substrate. Per hoppy's chart, this would put me in medium light but your findings show the PAR a bit lower.

Very interesting. What makes this tough is that even if you owned a PAR meter you'd have to buy and test the fixtures before you knew which one was best!
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post #157 of 776 (permalink) Old 10-13-2010, 04:59 PM
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Originally Posted by Dave-H View Post
I'm about to order a 2 x T5HO fixture from Catalina and mount it about 28 inches off the substrate. Per hoppy's chart, this would put me in medium light but your findings show the PAR a bit lower.

Very interesting. What makes this tough is that even if you owned a PAR meter you'd have to buy and test the fixtures before you knew which one was best!
Yeah exactly. I'm strongly considering purchasing one to have on hand at all times. But it's not an easy expense to justify for a meter that won't get used too often. I'm lucky I was able to borrow one from Tom

Individual testing is really the only way to know. It would be like trying to guess what our co2 levels are without the use of a drop checker, based on the BPS rate from other tanks. As we know, it would be ridiculous to even try and make this comparison. I feel the same goes for lighting, to a certain extent.

~ Jose



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post #158 of 776 (permalink) Old 10-13-2010, 05:06 PM
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Yea, but then again the stakes are different. If you are guessing at CO2 you can easily gas your fish. If you are guessing at light you will have a decent idea of what's going on after a while.

I'm gonna put my lights up, give it a month and see how things are looking. Mainly I just want to measure more things and get analytical.
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post #159 of 776 (permalink) Old 10-13-2010, 05:20 PM Thread Starter
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Jose, are you sure the Current/Nova fixture is T5HO and not T5NO? Your results look a lot more like NO results than HO.

The effect of putting aluminum foil in the T8 fixture is about what I would expect - it doesn't take a sophisticated reflector to double the light you get compared to no reflector at all.

In general your results, except for the Current/Nova data, look consistent with mine. There is scatter in the data, for sure. But, the charts do allow you to get in the right ballpark with lighting, something I don't know any other way to do.

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post #160 of 776 (permalink) Old 10-13-2010, 05:35 PM
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Jose, are you sure the Current/Nova fixture is T5HO and not T5NO? Your results look a lot more like NO results than HO.

The effect of putting aluminum foil in the T8 fixture is about what I would expect - it doesn't take a sophisticated reflector to double the light you get compared to no reflector at all.

In general your results, except for the Current/Nova data, look consistent with mine. There is scatter in the data, for sure. But, the charts do allow you to get in the right ballpark with lighting, something I don't know any other way to do.
Yeah, I'm positive. The bulbs were PowerGlo and LifeGlo T5HO. I think the issue may be the age of the bulbs. But as I mentioned, I didn't have any new bulbs to try out. Not to mention the overall design and reflectors of the Current fixture is very low quality when compared to the Catalina fixture.

~ Jose



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post #161 of 776 (permalink) Old 10-13-2010, 07:06 PM Thread Starter
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Is this the fixture: http://www.current-usa.com/novaextremet5hox2.html If so, that could explain the low PAR, since that appears to use reflectors that are barely wider than the bulb, leaving little room for light to get from the back of the bulb to the front. I have read that the really good reflectors increase the light output by more than 2.5 times, and these clearly aren't that good.

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post #162 of 776 (permalink) Old 10-13-2010, 07:12 PM
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Is this the fixture: http://www.current-usa.com/novaextremet5hox2.html If so, that could explain the low PAR, since that appears to use reflectors that are barely wider than the bulb, leaving little room for light to get from the back of the bulb to the front. I have read that the really good reflectors increase the light output by more than 2.5 times, and these clearly aren't that good.
Yeah, looks very similar, although mine didn't come with the legs. And yes, the bulbs are VERY close together. In fact, it's difficult to remove the bulbs at times because space is so tight. And the reflector is horrible. I would not recommend this fixture to anybody.

~ Jose



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post #163 of 776 (permalink) Old 10-13-2010, 09:35 PM
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Jose ~ Please let me know when you are done with the meter. I would like to test my tanks. I can wait till the next meeting, 11/2, if you are going.

Thanks ~ Anthony

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post #164 of 776 (permalink) Old 10-13-2010, 10:09 PM
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Jose ~ Please let me know when you are done with the meter. I would like to test my tanks. I can wait till the next meeting, 11/2, if you are going.

Thanks ~ Anthony
Sure, I'll let you know. Should be in the next few days.

~ Jose



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post #165 of 776 (permalink) Old 10-20-2010, 01:06 AM
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Heya lighting gurus, I have a question. How much light would a fixture with a rounded, painted white metal desk lamp with a 13w CF bulb over a 2.5g tank give me?


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