Plant Capable LED fixture and PAR Readings.

[jarrod0987]

So for the last 6 months I have been testing the Current U.S.A. LED+ Light. 28-36" model on my 20 gal planted tank. Photo period is 5 hours on 4 hours off 5 hours on 10 hours off.
It has approximately 1500 hours of burn in time as of this experiment.
For those of you who do not know. Plants need light of a certain color spectrum. It's more like a range. This range is known as PAR. It means Photosyntheticly Active Radiation. The subject of plant light color and intensity needs is a never ending story I will not get into here. I never read most of that book LOL.
I am one of the few people fortunate enough to be able to own a PAR meter. Mine is a Quantum Flux brand Apogee. The model is MQ-200. I decided to take some readings and share them with the community. The manufacturer has stated there meter is not accurate with LED lights. So my numbers are just for the curios.
This light fixture has 4 channels that control the various LEDs. It has white LED's that are mostly for visual appearance. It also has combination Red,Green, and Blue LED's which are what makes it "Plant Capable". Each color can be controlled separately. When you wish to set the fixture up for plants you use "Full Spectrum" mode which appears to turn all the lights on to the max.
Regarding my tank it is a 20 gal (Long Profile) Tank. It is about 30" long, 12" Front to back, and 12.5" Tall. The LED lights are About 1.5" from the surface of the water and 10" above the surface of the gravel. When you are close to the surface, the amount of light has a lot of variance. This is because the LED's are all point lights. The light has not spread out yet. So right under a LED will be a high reading but just off to the side of it has a much lower reading. The deeper you go, the more the light spreads out. So the variance will be much less. Also, the deeper you go, the water dissipates the light and the readings get lower.

I started with all the LED's fully on:
Just above the surface (In the air) I got
250-300 uM (Micro Moles)
Just below the surface (Under the water just barley)
220-280 uM
Half way to the gravel I got (About 5" deep)
22-105 uM (Plant leaves were causing huge variance)
At the surface of the gravel I got.
30-50 uM

With just the white LED's fully on and RGB LED's fully off I got:
Just above the surface (In the air) I got
180-300 uM
Just below the surface (Under the water just barley)
180-220 uM
Half way to the gravel I got (About 5" deep)
90-100 uM
At the surface of the gravel I got.
30-45 uM

With just the RGB LED's fully on and White LED's fully off I got:
Just above the surface (In the air) I got
50-60 uM
Just below the surface (Under the water just barley)
42-47 uM
Half way to the gravel I got (About 5" deep)
17-20 uM
At the surface of the gravel I got.
5-7 uM

With just the RED LED's fully on and all other LED's fully off I got:
Just above the surface (In the air) I got
16-17 uM
Just below the surface (Under the water just barley)
12-13 uM
Half way to the gravel I got (About 5" deep)
4-5 uM
At the surface of the gravel I got.
3 uM

With just the Green LED's fully on and all other LED's fully off I got:
Just above the surface (In the air) I got
14-17 uM
Just below the surface (Under the water just barley)
12-13 uM
Half way to the gravel I got (About 5" deep)
4-5 uM
At the surface of the gravel I got.
3 uM

With just the Blue LED's fully on and all other LED's fully off I got:
Just above the surface (In the air) I got
21-27 uM
Just below the surface (Under the water just barley)
18-23 uM
Half way to the gravel I got (About 5" deep)
6-8 uM
At the surface of the gravel I got.
3-5 uM
Enjoy the view.

 

[Brookster123]

Soo..... what do you think?? These par values have been available for some time

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[Aqua Vivarious]

I don't have anything technical to add but since getting back into fresh water planted aquariums about this time last year I become quite curious about finding some objective way to measure the PAR values by distance as you have, you beat me to it. I have shied away from CO2 injection and thus have mainly had success with the easy growers. my interest has oddly turned to fancy guppies, it's hard to explain why but it just is what it is (red lace russian, Topaz and Blue Grass ATFG's and some green cobra endlers). I now find myself less caught up about what types of plants I want to grow and rather focusing on what does well and will readily suck the nitrogen out of the water in the crowded breeder tanks. what started out as a curiosity has gradually mushroomed into an obsession with the creation of a heavily insulated fish room of 14 tanks and the tanks are spreading to the kids room, living room and soon there will be a rimless mr aqua 12 gallon long over top of my wife's home office desk. my lighting of choice has been finnex planted plus 24/7's because they are affordable and kept in stock at my favorite fish store... I now have 4, 48 inch lights and an assortment of others. I've gone crazy with the lights because I have noticed many benefits to keeping plants in the breeder tanks, more stable water chem, more hiding places for newborns trying to escape voracious mothers and an endless supply of plants for our show tank landscaping. What has become apparent is that if chemistry is kept in reasonable parameters it's almost impossible on one hand to have too much light while on the other hand, plants adjust to what they are given, within reason. obviously in nature light exposure is not constant, with shading varying quite a bit. I wish I had a way to measure the light output. I've had some friends have decent success with low light nono tanks, surely some of the lowest output LED's out there making me very curious as to how they maintain the stability, it's like some plants are capable of idling at a very low PAR level. I can see experimenting going both ways, with minimal light in the KISS (keep it super simple) vein all the way to using two light strips over a given tank. As you have noted, the PAR value drops off quickly. have you tried testing finnex, I'd be curious as to how they measure up?

 

[jarrod0987]

I don't have anything technical to add but since getting back into fresh water planted aquariums about this time last year I become quite curious about finding some objective way to measure the PAR values by distance as you have, you beat me to it. I have shied away from CO2 injection and thus have mainly had success with the easy growers. my interest has oddly turned to fancy guppies, it's hard to explain why but it just is what it is (red lace russian, Topaz and Blue Grass ATFG's and some green cobra endlers). I now find myself less caught up about what types of plants I want to grow and rather focusing on what does well and will readily suck the nitrogen out of the water in the crowded breeder tanks. what started out as a curiosity has gradually mushroomed into an obsession with the creation of a heavily insulated fish room of 14 tanks and the tanks are spreading to the kids room, living room and soon there will be a rimless mr aqua 12 gallon long over top of my wife's home office desk. my lighting of choice has been finnex planted plus 24/7's because they are affordable and kept in stock at my favorite fish store... I now have 4, 48 inch lights and an assortment of others. I've gone crazy with the lights because I have noticed many benefits to keeping plants in the breeder tanks, more stable water chem, more hiding places for newborns trying to escape voracious mothers and an endless supply of plants for our show tank landscaping. What has become apparent is that if chemistry is kept in reasonable parameters it's almost impossible on one hand to have too much light while on the other hand, plants adjust to what they are given, within reason. obviously in nature light exposure is not constant, with shading varying quite a bit. I wish I had a way to measure the light output. I've had some friends have decent success with low light nono tanks, surely some of the lowest output LED's out there making me very curious as to how they maintain the stability, it's like some plants are capable of idling at a very low PAR level. I can see experimenting going both ways, with minimal light in the KISS (keep it super simple) vein as well as using two light strips over a given tank. As you have noted, the PAR value drops off quickly, I may try double strands of lights to see what the upper limits are. have you tried testing finnex, I'd be curious as to how they measure up?

No I never tried them. I don't inject CO2 either. I do dose Excel but I'm not sure it helps growth rate. It did reverse some twisty Amazon leaves I had.

 

[Brookster123]

Removed

Ya know what Brookster123, you win.

Article available on request.

Huh?? What did I win?? Par is becoming less interesting to me these days.. finnex planted plus was the dark horse in par readings for a while but I've "found" it to be a quite capable light. Just curious what you "thought" of the current??

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[jarrod0987]

It works. for the 1st 4 of 5 months growth was super slow to the point I thought maybe it was just barley enough to sustain life. In the last month, once the plants got up to the highest 1/3 of the tank there growth exploded. They doubled there size in that month.

Also, it Remembers how you have it set when it is off so you can use it with a timer. It seems to remember during power outages too but I don't know for how long.

I apologize. I misunderstood your comment.

 

[Brookster123]

I used 2 on a 16" tall tank and had pretty good results. Just using one on the same tank was rather dissapointing. I shelf'd it for a finnex 24/7.

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