need help with calculating PAR for my tank - The Planted Tank Forum
 
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post #1 of 14 (permalink) Old 03-26-2015, 05:35 PM Thread Starter
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need help with calculating PAR for my tank

I would like to know if anyone here measured the PAR of finnex ray2 and finnex planted plus under 24" of water.
My setup is a 125 gal tank 72x18x21 and I have 2 led's fixtures, one is a finnex ray 2 7000k 48" and second is a finnex planted plus 48" . They are lifted about 3" from the surface of the tank, giving me a distance of 24" to substrate .The lamps are mounted one next to the other.
I lifted them 3" so they will cover the 12" gap I have on each end.
I've seen the PAR data for these fixtures but nothing under water.
I'm trying to figure out if my setup is low, med or high.
Any help is appreciated.
Thanks.
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post #2 of 14 (permalink) Old 03-26-2015, 05:44 PM
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Quote:
Originally Posted by cbucner View Post
I would like to know if anyone here measured the PAR of finnex ray2 and finnex planted plus under 24" of water.
My setup is a 125 gal tank 72x18x21 and I have 2 led's fixtures, one is a finnex ray 2 7000k 48" and second is a finnex planted plus 48" . They are lifted about 3" from the surface of the tank, giving me a distance of 24" to substrate .The lamps are mounted one next to the other.
I lifted them 3" so they will cover the 12" gap I have on each end.
I've seen the PAR data for these fixtures but nothing under water.
I'm trying to figure out if my setup is low, med or high.
Any help is appreciated.
Thanks.
The through air figures will be close enough. There is some basis to assume they are a bit low due to tank glass reflections and water refraction.
Then they may be a bit low due to absorption of particular wavelengths ect.
RayII's being short in red do not really have that problem.
Only really good way is to measure your tank at your height..

adding the 2 at 24" will be a "close enough" number.

"A man with a watch knows what time it is. A man with two watches is never sure."
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post #3 of 14 (permalink) Old 03-26-2015, 06:17 PM Thread Starter
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I've watched an you tube video of the 48" planted plus at 19" under water measured with a PAR Meter and it was just around 20 PAR right under it .
With no water PAR data for plated plus is around 40 at 24", so water does matter , were looking at half PAR .
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post #4 of 14 (permalink) Old 03-26-2015, 06:23 PM
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If you're concerned whether or not it's "enough light" at 24 inches - you can check my tank journals.

I use a Ray2 and a Planted+ combination in my 92g Corner - zero problems with a variety of plants, including DHG

120g Nano Paradise
- Dwarf Emerald Rasboras, Glowlight Danios, Ember Tetras, Scarlet Badis, RCS, Assassin Snails, Neirite Snails, Black Molly, Dwarf Gourami

coming soon: CPDs!

http://www.plantedtank.net/forums/sh...881&highlight=
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post #5 of 14 (permalink) Old 03-26-2015, 06:24 PM Thread Starter
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Here's the link to the youtube video
https://youtu.be/-I-fUrI5mwo
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post #6 of 14 (permalink) Old 03-26-2015, 06:44 PM
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Quote:
Originally Posted by cbucner View Post
Here's the link to the youtube video
https://youtu.be/-I-fUrI5mwo
AFAICT that is a stingray..and weaker than any of the 2 you mentioned.

Here is an "in water" measurement of a Planted plus:


much depends on length but I'm still sticking w/ this number:


Why such short lights over such a wide tank?? if you are putting them "end to end" sort of your PAR is low.. Together your PAR in the middle will be like 60-70 (and likely low) guesstimate..and likely low

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Last edited by jeffkrol; 03-26-2015 at 07:04 PM. Reason: par
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post #7 of 14 (permalink) Old 03-26-2015, 07:02 PM
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Agreed, that's a stingray, which explains the 10 PAR reading in the video... that's a low output fixture intended for low light at 12-18" deep or medium-high in really shallow tanks (ie: 6-8"). It has no business being on a tall tank unless being used as part of a multi-light setup.

Also, for what its worth the Finnex provided numbers for a 48" ray2 at 24" deep is 50 PAR on-center.

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post #8 of 14 (permalink) Old 03-26-2015, 07:35 PM Thread Starter
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The light in the video on the first tank is a planted plus not a stingray. Towards the end the guy uses a stingray on a second tank.
So I dont know where u got the par data , maybe finnex but that is not under water, video cant lie. Please watch video and will see that on the first tank he uses the costco light and then a planted plus not stingray.

I'm not trying to disagree but just get the facts right for everybody outhere to know.

Bump: Lights are side by side not end to end .
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post #9 of 14 (permalink) Old 03-26-2015, 07:46 PM Thread Starter
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If the smaller nr means par under water and the bigger nr means par in thin air then it all makes sense.
At 24" inches under water guestimate will be right under 20Par for the ray II and since planted plus is a little under ray II , I can say 15 par at 24 under water then I would have about 35 - 40 par center under the lights at 24 " which is a far cry from what some think that they will have about 100 par like under thin air.
Does that makes sense or not ?
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post #10 of 14 (permalink) Old 03-26-2015, 07:53 PM
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Quote:
Originally Posted by cbucner View Post
The light in the video on the first tank is a planted plus not a stingray. Towards the end the guy uses a stingray on a second tank.
So I dont know where u got the par data , maybe finnex but that is not under water, video cant lie. Please watch video and will see that on the first tank he uses the costco light and then a planted plus not stingray.

I'm not trying to disagree but just get the facts right for everybody outhere to know.

Bump: Lights are side by side not end to end .
Ok first that video has a heavily tannen-ed tank so there is a lot of blue absorption


Secondly "other numbers" IN a tank..
Quote:
my par readings. opinions?

August 5th, 2014, 02:12 PM


Rented a par meter to see where I was at since I got a new light. On my 150g I have a current usa satellite led plus and finnex planted+ Both 48" leds. Both lights are 30" from substrate. readings were.

satellite plus.

18" 40
24" 30
30" 15


Planted+

18" 60
24" 40
30" 25
http://www.azaquaticplants.com/forum...dings-opinions

If you have pee colored water the video will probably be correct..

but in gin clear tanks PAR will be 60 plus w/ 2 lights at 24"....

another video for you:
https://youtu.be/vD7QaRzf1Qw

60 at 16"...not real different than my planted plus chart (+/- 10%) OR the other one. Certainly not in line w/ the video you posted..if you assume the following numbers are correct there is no way 24"=20PAR over a clear water tank.

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Last edited by jeffkrol; 03-26-2015 at 08:17 PM. Reason: video
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post #11 of 14 (permalink) Old 03-26-2015, 08:42 PM
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Quote:
Originally Posted by cbucner View Post
If the smaller nr means par under water and the bigger nr means par in thin air then it all makes sense.
At 24" inches under water guestimate will be right under 20Par for the ray II and since planted plus is a little under ray II , I can say 15 par at 24 under water then I would have about 35 - 40 par center under the lights at 24 " which is a far cry from what some think that they will have about 100 par like under thin air.
Does that makes sense or not ?
First things first... ignore the PAR data for the planted+ from that video (at around 9:19). There's so many things wrong with the measurement that it would be very hard to correct them and try to use in any kind of general sense for your average tank. The Apogee Par meter they used is not sensitive to 660nm, but the planted+ has quite a lot of output up there. Also they have somewhat tannic water, as jeff mentioned. Unless your tank water is also that tint, this adds another layer of error to the measurement.

It makes no sense at all to try to estimate the Ray2's par based on a particularly unusual measurement of planted+ par.

In-water PAR is generally speaking higher than in-air, unless your water is really deep (over 24") and/or has something in it that absorbs a lot of light (tannin, bacterial bloom, etc). This is because the water-air boundary acts as a focusing lens, concentrating the light into a smaller spot when it enters, thus increasing par. Water absorbs more light than air, so eventually it can counter this effect, but that typically doesn't happen with good, clear water in a normal tank.

New to planted tanks, avid gardener/tinkerer.
36g bow tank journal Fluval C4 + Quietflow 30, Finnex Planted+ with dimmer mod, low-tech.
10 gallon secondary tank with Finnex stingray with dimmer mod, AC20, low tech
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post #12 of 14 (permalink) Old 03-26-2015, 10:47 PM
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From a "Hoppy Study"


Lighting an Aquarium with PAR instead of Watts

Granted only 5"

"A man with a watch knows what time it is. A man with two watches is never sure."
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post #13 of 14 (permalink) Old 03-27-2015, 01:07 AM Thread Starter
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Now we're getting there, my water is super clear, have an uv sterlizer, so I should have 40 from the planted + , the ray 2 shoud be at least the same so let's say about 40 ish too so for both lights lets say 70 PAR. Is this a med or high light setup?
The problem I'm having is that I get algae growth on the older leaves , the ones about a week old. So should I raise the setup a little higher or turn the times down from 8h.
Co2 is at appx 40ppm. Ferts pps pro.
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post #14 of 14 (permalink) Old 03-27-2015, 01:59 AM
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Anything over 50 is high light.

That said, the ray2 is 50 through 24" of air, so it should be roughly the same, maybe a tad higher through nice clear water.

I'd say closer to 85, but we're splitting hairs here...

New to planted tanks, avid gardener/tinkerer.
36g bow tank journal Fluval C4 + Quietflow 30, Finnex Planted+ with dimmer mod, low-tech.
10 gallon secondary tank with Finnex stingray with dimmer mod, AC20, low tech
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