Par/ light intensity question - The Planted Tank Forum
 
LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old 11-07-2019, 11:05 PM Thread Starter
Algae Grower
 
butchblack's Avatar
 
PTrader: (0/0%)
Join Date: Oct 2019
Location: Waltham, Massachusetts, USA
Posts: 49
Par/ light intensity question

HI

Question about PAR and light intensity. I found a couple of conversion sites that has enabled me to use my photo light meter to go from ev, to lux, to PAR (PPFD) I'm getting a reading of between 172 and 176 umol/s/m2. My tank is dry at the moment, but if that's the par reading it seems high. My questions are 1. is the umol/s/m2 reading the par reading? 2. how much loss can I expect when I fill the tank with water? It's a 75 gallon tank?

The good news is that just by observation, it looks like I'll have plenty of light, and the light I'm using can dim to zero. The color temp is also adjustable from 20K to 65K, Though I like it best at 53K-55K at the moment.

The real fountain of youth is being a musician
butchblack is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old 11-09-2019, 07:32 AM
Wannabe Guru
 
PTrader: (0/0%)
Join Date: Jun 2017
Posts: 1,181
Quote:
My questions are 1. is the umol/s/m2 reading the par reading?
Yes that is par. I don't know how much light will be absorbed by the water But I suspect the water effect will be will be small.
Surf is offline  
post #3 of 12 (permalink) Old 11-09-2019, 03:00 PM Thread Starter
Algae Grower
 
butchblack's Avatar
 
PTrader: (0/0%)
Join Date: Oct 2019
Location: Waltham, Massachusetts, USA
Posts: 49
Cool. If my calculations are correct I'm going to have more than enough light. The next step is to get the tank filled, planted, and running and see how the light works.

The real fountain of youth is being a musician
butchblack is offline  
 
post #4 of 12 (permalink) Old 11-10-2019, 11:23 AM
Planted Member
 
PTrader: (0/0%)
Join Date: Nov 2013
Location: Illinois
Posts: 219
172 par,,, is that at the top of the tank?

check at the bottom.
To go from lux to par divide lux buy 70.

What is the lighting setup?
Jbubba001 is offline  
post #5 of 12 (permalink) Old 11-10-2019, 03:16 PM Thread Starter
Algae Grower
 
butchblack's Avatar
 
PTrader: (0/0%)
Join Date: Oct 2019
Location: Waltham, Massachusetts, USA
Posts: 49
Quote:
Originally Posted by Jbubba001 View Post
172 par,,, is that at the top of the tank?

check at the bottom.
To go from lux to par divide lux buy 70.

What is the lighting setup?
Thanks. I rechecked it. My ev was 10.9 which translated to 5000 lux, divided by 70 gives me 71.42 PAR. Still a high number, but more in line than the 172 I got before. I did the light meter reading in a dry tank at the bottom.

I'm actually using a photo/video LED light, a GVM 560as. A nice light with both a high CRI and TLCI of 97. We'll see how well it does when the tank gets filled and planted.

The real fountain of youth is being a musician
butchblack is offline  
post #6 of 12 (permalink) Old Yesterday, 11:38 AM
Algae Grower
 
PTrader: (0/0%)
Join Date: Jan 2010
Location: rochester, ny
Posts: 22
i would NOT trust a light meter for conversions to par esp if you are using full spectrum. like NOT at all. rent a PAR meter! www.bulkreefsupply.com
becon776 is offline  
post #7 of 12 (permalink) Old Yesterday, 11:40 AM
Algae Grower
 
PTrader: (0/0%)
Join Date: Jan 2010
Location: rochester, ny
Posts: 22
this
Attached Thumbnails
Click image for larger version

Name:	15735587334641058401003952415693_1573558812454.jpg
Views:	7
Size:	3.59 MB
ID:	889335  

becon776 is offline  
post #8 of 12 (permalink) Old Yesterday, 01:38 PM Thread Starter
Algae Grower
 
butchblack's Avatar
 
PTrader: (0/0%)
Join Date: Oct 2019
Location: Waltham, Massachusetts, USA
Posts: 49
Quote:
Originally Posted by becon776 View Post
i would NOT trust a light meter for conversions to par esp if you are using full spectrum. like NOT at all. rent a PAR meter! www.bulkreefsupply.com
My concern is having enough light intensity and a decent color spectrum for growing plants. It looks like I will have both. I think that renting a PAR meter would be overkill for me.

The real fountain of youth is being a musician
butchblack is offline  
post #9 of 12 (permalink) Old Yesterday, 02:03 PM
Algae Grower
 
SpringHalo's Avatar
 
PTrader: (2/100%)
Join Date: Oct 2017
Location: Michigan
Posts: 112
Quote:
Originally Posted by butchblack View Post
Thanks. I rechecked it. My ev was 10.9 which translated to 5000 lux, divided by 70 gives me 71.42 PAR. Still a high number, but more in line than the 172 I got before. I did the light meter reading in a dry tank at the bottom.

I'm actually using a photo/video LED light, a GVM 560as. A nice light with both a high CRI and TLCI of 97. We'll see how well it does when the tank gets filled and planted.

That 70-ish value works fine for standard white LEDs which is what your fixture uses. The actual numbers will vary slightly from ~65 (3000k) and ~75 (6500k), but your meter probably has 10-20% error anyway. The lux meter will give you a good rough idea of your PAR which is fine for just setting up. Remember it's better to have too little light than too much; you can always bump it up later and most plants won't die from lack-of-light.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
SpringHalo is offline  
post #10 of 12 (permalink) Old Yesterday, 08:57 PM
Algae Grower
 
PTrader: (0/0%)
Join Date: Jan 2010
Location: rochester, ny
Posts: 22
sorry if i seemed abrupt. i just got done dealing with mapping out all the PAR for my reef. Literally had my lights set way off. was 500 par on the substrate and 750 at the top of the stack. :-0

so i wonder what is the upper range preferable PAR for very demadnjng plants. i mean the sun is pretty strong? i know for my sps corals i target around 500. i mean most of our plants are tropical. so if you are dosing co2 and nutrients via a dosing pump where is the sweet spot?
becon776 is offline  
post #11 of 12 (permalink) Old Yesterday, 09:30 PM Thread Starter
Algae Grower
 
butchblack's Avatar
 
PTrader: (0/0%)
Join Date: Oct 2019
Location: Waltham, Massachusetts, USA
Posts: 49
Quote:
Originally Posted by becon776 View Post
sorry if i seemed abrupt. i just got done dealing with mapping out all the PAR for my reef. Literally had my lights set way off. was 500 par on the substrate and 750 at the top of the stack. :-0

so I wonder what is the upper range preferable PAR for very demanding plants. I mean the sun is pretty strong? I know for my sps corals I target around 500. I mean most of our plants are tropical. so if you are dosing co2 and nutrients via a dosing pump where is the sweet spot?
I'm in the process of setting the tank up. My CO2 system should be here Thursday, hopefully have everything set up by the weekend, then I can order some plants. At the moment,I'm planning on manually fertilizing, so no dosing pumps.

The real fountain of youth is being a musician
butchblack is offline  
post #12 of 12 (permalink) Old Yesterday, 09:51 PM
Planted Tank Guru
 
PTrader: (0/0%)
Join Date: Jun 2013
Location: WI
Posts: 11,354
Sun can hit 2000 "PAR" at water surface.. Thing is that's like high noon.. as the sun angle increases PAR decreases so it's sort of comes down to the term.. DLI or daily light integral..


Quote:
Here is the formula for calculating DLI with a quantum meter.
μmol m-2s-1 x (,3600 x photoperiod) / 1,000,000 = DLI
- μmol m-2s-1 is a reading, or averaged readings, from the quantum meter
- 3,600 is the number of seconds in an hour
- Photoperiod is the period (in hours) of light exposure per 24 hours
- 1,000,000 is the number of μmols per mole

For example, 38.1 μmol m-2s-1 x 3600 seconds/hour x 12 hour photoperiod / 1000000 μmoles/mol = 1.6 mol. m-2d-1 (or 1.6 moles/day).

The more scheduled readings a user takes with their quantum meter throughout the day, the more representative the data becomes. You can substitute an averaged reading (per day) for the single reading in the above equation.
The photoperiod in the equation serves to estimate values for missed measurements, and can be removed from the equation in a scenario where readings are consistently taken throughout the day (such as item 3501 Greenhouse Growth Tracker).
Formula taken from Jim Faust? Light Management I (of III) article found in Spectrums articles section (#A050)
You can hit 40 moles of photons over a day in the open in FL in June w/ 12hrs of daylight.
A tank w/ 100PAR at the substrate over 12 hours is like 4.3...

In a reef tank you hit like 10 (using the generally accepted 200-300PARE for sps if I remember correctly)...18 w/ 500PAR over 10 hour photoperiod..
you can actually exceed "normal" in ocean on the equator daylight exposure in the upper levels of some reef tanks. I don't think a lot of reefers really understand that..or believe it.



Quote:
Analyses of data revealed the following DLIs:

'Air' DLI = 30 Mol photons/Day
'Reef' DLI = 16 Mol photons/Day
https://www.advancedaquarist.com/2009/5/aafeature
See your 500 PAR if a 10 HR photoperiod actually exceeds a natural reef exposure..
Point is outside doesn't really count..

Thing is you can add as much light as your other factors of CO2 and fertilizer can handle..Problem it's easy to get unbalanced..
Not to mention each species has it's own tolerances for low and high light..

Many demanding plants apparently can be grown w/ lower light in the presence of adequate CO2.

Anyways an answer to your question..


Quote:
STRENGTH
"Sufficient PAR at the right depth
​The light should produce sufficient PAR at the substrate depth of your tank.
Rough guidelines as commonly used by aquatic plant community as follows -

20-30 umols (PAR)
​Low lighting - suitable for shade aquarium plants.

50 umols (PAR)
Medium Lighting. With good CO2, you can grow any commercially available plant, but may not get the most intense coloration in colored plants. Good for carpets.

90+ umols (PAR)
​High lighting - Good for red/colored aquarium plants. Allows for greater density and self-shading effects. Requires good control of tank cleanliness and plant health to avoid algae issues.
https://www.advancedplantedtank.com/light-3pillars.html

"A man with a watch knows what time it is. A man with two watches is never sure."

Last edited by jeffkrol; Yesterday at 10:05 PM. Reason: edit
jeffkrol is offline  
Reply

Tags
None

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome