What par meter for freshwater ? - Page 2 - The Planted Tank Forum
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post #16 of 28 (permalink) Old 10-24-2020, 03:31 PM
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Thanks. I had watched that video before buying my Seneye and, based upon this and other research, came to the conclusion that the Seneye value was higher than their competitors if only concerned about light readings directly (or slightly outside) under the light, which was my primary interest. It seems that this is still the case.
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post #17 of 28 (permalink) Old 10-25-2020, 02:21 PM
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I have the seneye and it works well enough. Have used a couple others. Honestly, exact PAR values are irrelevant. It does not matter if your lighting produces 90 vs 100 par. A balanced tank will not care. The main concern is knowing the range. Are we talking 20ish par, 50ish, 100ish, 300...? As long as the meter used will get you close (IMO within 20%), it's all you need.


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post #18 of 28 (permalink) Old 10-25-2020, 03:09 PM
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+1 for the Seneye, I use one and it comes in handy when making DIY fixtures.

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post #19 of 28 (permalink) Old 10-26-2020, 02:15 PM
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Quote:
Originally Posted by Sarlindescent View Post
I have the seneye and it works well enough. Have used a couple others. Honestly, exact PAR values are irrelevant. It does not matter if your lighting produces 90 vs 100 par. A balanced tank will not care. The main concern is knowing the range. Are we talking 20ish par, 50ish, 100ish, 300...? As long as the meter used will get you close (IMO within 20%), it's all you need.
Right. You don't need precise values of PAR as ballpark figures are sufficient to determine if you can grow low, medium or high light plants.

You don't need an expensive PAR meter over $300 to measure precise PAR underwater. A cheap substitute I use is a LUX meter sold under $30 for photography to measure LUX and convert LUX to PAR. The conversion factors vary with the light sources and for LEDs, PAR can be estimated by dividing LUX by a conversion factor of 70. Since the LUX meter cannot measure underwater, you have to drain down the tank to measure LUX in air, considering that actual PAR will increase when the tank is filled due to reflection from glass containment.
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post #20 of 28 (permalink) Old 10-29-2020, 08:05 AM Thread Starter
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You don't need a precise number - i agree. But if the error is large or wildly inconsistent across different lights then it becomes irrelevant. I'm not claiming this is the case but the relatively low reviews on reef-bulk and amazon left me concern.

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I have the seneye and it works well enough. Have used a couple others. Honestly, exact PAR values are irrelevant. It does not matter if your lighting produces 90 vs 100 par. A balanced tank will not care. The main concern is knowing the range. Are we talking 20ish par, 50ish, 100ish, 300...? As long as the meter used will get you close (IMO within 20%), it's all you need.
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post #21 of 28 (permalink) Old 10-29-2020, 06:02 PM
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What I use - Apogee MQ-510.
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post #22 of 28 (permalink) Old 10-30-2020, 04:42 PM Thread Starter
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I think i'll go with the 510 but i'll wait for a sale. $500 seems a bit steep right now. There is an mq-500 but not sure how it differs.
--
Difference bewteen 500 and 510 is 510 corrects for being under-water. Also price difference is small.

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What I use - Apogee MQ-510.

Last edited by jake21; 10-30-2020 at 04:55 PM. Reason: looked up difference between 510 and 500
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post #23 of 28 (permalink) Old 10-30-2020, 06:50 PM
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I bought the older model apogee sensor for usb (which is still available and about half the cost of their newer model). What numbers I saw is that unless you are really concerned with measuring light strength at the extremes (really really blue, or really really red) its going to work fine. Since we try to keep our lights as natural looking as possible its going to be (essentially) just as accurate as their newer sensor. Plus it will handle light at other angles then straight up and down as opposed to the seneye which becomes quickly inaccurate at other angles. I have been very happy with it. I also bought a selfie stick I mutilated to make a little holder for it. I definitely recommend either buying their holder or doing something similar.



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post #24 of 28 (permalink) Old 11-02-2020, 12:14 AM Thread Starter
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If that is the model i'm thinking of it requires a pc near the tank. I don't have a laptop and if i did have a laptop it would run linux and not windows - so to use it i would have to get a laptop and then cross my finger that their software runs under wine (linux window's sort of emulator for windows programs).

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I bought the older model apogee sensor for usb (which is still available and about half the cost of their newer model). What numbers I saw is that unless you are really concerned with measuring light strength at the extremes (really really blue, or really really red) its going to work fine. Since we try to keep our lights as natural looking as possible its going to be (essentially) just as accurate as their newer sensor. Plus it will handle light at other angles then straight up and down as opposed to the seneye which becomes quickly inaccurate at other angles. I have been very happy with it. I also bought a selfie stick I mutilated to make a little holder for it. I definitely recommend either buying their holder or doing something similar.
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post #25 of 28 (permalink) Old 11-02-2020, 01:39 PM
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If that is the model i'm thinking of it requires a pc near the tank. I don't have a laptop and if i did have a laptop it would run linux and not windows - so to use it i would have to get a laptop and then cross my finger that their software runs under wine (linux window's sort of emulator for windows programs).
Yeah if you don't have a laptop then it doesn't make sense to buy a usb sensor be it apogee or seneye. You just need to bite the bullet and buy the apogee with attached reader. Technically you can make your own reader using the usb and a multi meter but personally I wouldn't go that route. I have several laptops lying around from various work and personal computer generations so it was an easy choice.



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post #26 of 28 (permalink) Old 11-02-2020, 01:58 PM
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Quote:
Originally Posted by minorhero View Post
Yeah if you don't have a laptop then it doesn't make sense to buy a usb sensor be it apogee or seneye.
The Seneye seems to work perfectly fine on both my iPad and phone using the optional wireless web server.
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post #27 of 28 (permalink) Old 11-12-2020, 03:26 PM
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The conversion factors vary with the light sources and for LEDs, PAR can be estimated by dividing LUX by a conversion factor of 70. Since the LUX meter cannot measure underwater, you have to drain down the tank to measure LUX in air, considering that actual PAR will increase when the tank is filled due to reflection from glass containment.
Verrry interesting! I have a Sekonic L-308X-U, so I'll try measuring my lights. My lights are suspended 9 inches above the normal waterline, and the tank is 24" deep, minus about 3" of substrate. I guess I can take an incident reading at the waterline (and perhaps another one with a glass pitcher of water to approximate how much light falloff to account for) and apply that 70% conversion factor. Very rough guesstimate, but a useful one, I would think. A relative measurement is useful for my needs.

Last edited by Flow; 11-12-2020 at 03:30 PM. Reason: one more time
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post #28 of 28 (permalink) Old 11-12-2020, 04:06 PM
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There are numerous examples of conversion figures on the net.

Indirectly ( one can calculate it):
https://www.google.com/url?sa=t&sour...efPz7WLLzLKPHA

1par = 75 lux w/ a low cri 6500k led

Dividing lux by 70 is good enough.
With "visibly whitish" leds it could go down to like 39. My personal ild number was 60-65.

Comparing my lux meter, seneye, and that calculator showed it's fairly accurate.

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