# Philips T8 LED Has anyone used these bulbs?



## Monrankim (May 28, 2016)

I use a 48" t8 shoplight for my 75 gallon low tech dirt tank. When I saw these Philips "daylight" t8 LED bulbs that pop right into a t8 light at Home Depot for just under $7, I couldn't resist giving it them a shot. I was using 32w 6500k bulbs before but the LEDs are 17w 5000k.
I put them in and the color is pleasant enough. Looking at the bulbs directly I could see blue in the 6500k bulb as opposed to the LED.
Does anybody have experience with these bulbs or know if they will be equivalent to the output if the t8's?


----------



## jeffkrol (Jun 5, 2013)

Your t8's probably initially produce around 2800 lumens per tube.
Those LED's are rated at 2100 lumens per tube..about 33% less output.

BUT there is a catch, because of the LED output geometry, the lumens getting to your plants is, as some have estimated, 2x more efficient.
This overcomes any lack of native output equivalence.
Of course things like the reflectors for the tubes can increase or decrease that deficit.

Bottom line, probably pretty equivalent w/ an advantage to the LED's


----------



## Monrankim (May 28, 2016)

jeffkrol said:


> Your t8's probably initially produce around 2800 lumens per tube.
> Those LED's are rated at 2100 lumens per tube..about 33% less output.
> 
> BUT there is a catch, because of the LED output geometry, the lumens getting to your plants is, as some have estimated, 2x more efficient.
> ...


Thank you for the informative reply. I didn't know about the added advantage of LED. Good to know that it is roughly equivalent with a plus because I am happy with the change otherwise. It's a 4 bulb shop light and I'm running 2 bulbs, so if it wasn't going to be enough light, I could simply add another one. Better to know I don't need to now rather than learning the hard way with an algae bloom.


----------



## Monrankim (May 28, 2016)

My crypts started reaching up. I don't think it is the same intensity of light


----------



## PlantedRich (Jul 21, 2010)

One of the big things for me to learn was that we can all make guesses and hope we are correct but that depends on how good the info we started with. On the other hands, learning to read the plants and do what they say, tends to give me better results. Right now it seems your plants are saying you missed a bit so I would go for adding another tube. 
I think they give you a much better shot at getting the right answer but I sure wish they would get back to me quicker and without so much hedging the bet!!!


----------



## jeffkrol (Jun 5, 2013)

Get a Lux or lumen app for your phone. Measure both @ about 1ft from the light..
I assume you rotated the LED tubes to be the correct down position?
Where are the plants in relation to the light?
LED's are fairly directional. If you got the plants in b or f and the light centered, they may stretch to the center.
There are a few possibilities here..and less light could be one. Need some #'s...

It does get a bit complicated.. 
http://www.ledsmagazine.com/article...tack-up-against-ballast-bypass-led-lamps.html



> In the prismatic K12 lensed troffer, 10 of the lamps provided lumen output comparable to the fluorescent and one lamp provided higher lumen output, with 20 lamps measuring lower output. Higher efficacy was maintained with K12 lensed and parabolic troffers, while recessed indirect troffers tend to reduce the efficiency of LED lamps to below that of fluorescents unless the LED lamp uses a high beam angle (Fig. 3). The Caliper study also indicated that observers preferred LED lamps with diffuse covers over clear lamps, and the diffuse lamps also lead to a luminous intensity distribution closer to that of a fluorescent tube's distribution, which is also preferred...."When people test our lamps either alone or in the troffers, we don't want them to perceive worse light or insufficient light; we want it to match their previous experience or be slightly better," said Jeff Hungarter, product portfolio manager at Cree.











older data obviously..
http://www.ledsmagazine.com/article...popular-led-t8-lamps-and-linear-fixtures.html


----------



## Monrankim (May 28, 2016)

PlantedRich said:


> One of the big things for me to learn was that we can all make guesses and hope we are correct but that depends on how good the info we started with. On the other hands, learning to read the plants and do what they say, tends to give me better results. Right now it seems your plants are saying you missed a bit so I would go for adding another tube.
> I think they give you a much better shot at getting the right answer but I sure wish they would get back to me quicker and without so much hedging the bet!!!


I couldn't agree more. Watching your plants and learning how to read your tank is an essential element in what we do it or at least it should be. With out that, there is no connection to the subject.

In the short time I used these bulbs..








The L Repens started losing color








And my Crypts flagged me down to change the light back



jeffkrol said:


> Get a Lux or lumen app for your phone. Measure both @ about 1ft from the light..
> I assume you rotated the LED tubes to be the correct down position?
> Where are the plants in relation to the light?
> LED's are fairly directional. If you got the plants in b or f and the light centered, they may stretch to the center.
> ...


Thanks for the info, I will definitely check the app out as well. As far as this experiment, I took the bulbs out because of the drastic changes I saw in the plants. I definitely need to do more homework on LEDs. This experiment was done on the fly between hectic work days with out research beforehand. I had the lights faced in the right direct (sticker in the back) and centered but I had two bulbs the first day and three bulbs thereafter, so it should have had decent coverage. What bothered me the most is that they were almost directly over the crypts and they still were reaching.


----------



## jeffkrol (Jun 5, 2013)

Monrankim said:


> Thanks for the info, I will definitely check the app out as well. As far as this experiment, I took the bulbs out because of the drastic changes I saw in the plants. I definitely need to do more homework on LEDs. This experiment was done on the fly between hectic work days with out research beforehand. I had the lights faced in the right direct (sticker in the back) and centered but I had two bulbs the first day and three bulbs thereafter, so it should have had decent coverage. What bothered me the most is that they were almost directly over the crypts and they still were reaching.


Hope you get a chance to do some measurements..
not quite convinced it is "quantity" that is the leading cause.. More like a different quality..
You should def. have more light w 3 LED tubes vs 2 t8's..

your crypts "pointing" up can well be a response to more light..
It is not uncommon..









Leaves in low light have a tendency to "flatten" to increase surface area.


----------



## Monrankim (May 28, 2016)

jeffkrol said:


> Hope you get a chance to do some measurements..
> not quite convinced it is "quantity" that is the leading cause.. More like a different quality..
> You should def. have more light w 3 LED tubes vs 2 t8's..
> 
> ...


Correct me if I'm wrong but in the picture it says that the vertical position of the leaves indicate the plant has high photosynthetic compacity, meaning the plant is arranging itself in a way to increase photosynthesis. The horizontal leaf position, (low photosynthetic compacity) would indicate that the plant does not need to increase its capacity due to an abundance of light. A sun plant will need as much light as it can get and reach while a shade plant will flatten. What I got from that is when a shade plant (Crypt Wentii) increases photosynthetic compacity, it needs more light.

I would like to be mistaken because I like those bulbs. I will take some measurements soon because I'm curious now.


----------



## jeffkrol (Jun 5, 2013)

It is a little confusing.. but I look at it this way.. say between 10-3 o'clock the suns rays are relatively perpendicular to the surface of the earth.
If one wanted to maximize light capture you would want your leaves parallel to the ground not "pointing" up..









Best explained here:
Solved: Chapter 4.1 Problem 2QE Solution | Elements Of Ecology 8th Edition | Chegg.com










One thing I can pretty well guarantee is changing light in any manner will affect the plants. Be it intensity or spectrum (i.e K) or both..

Generally speaking , in a botanical sense, most aquatics are considered "low light" plants. They will reach light saturation points faster than "high light" plants.
And have lower low light compensation points..
Though in an aquarium setting these "low light" plants still need "high light" ..
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC542304/?page=7
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC542304/?page=8
>15 to 55PAR to be above their low light compensation point where growth can occur..

Matter of semantics..


----------



## jeffkrol (Jun 5, 2013)

Found this.. a test of PAR w/ a shop light:
https://youtu.be/-I-fUrI5mwo

3700 lumen light 4000K (2 tubes)
27PAR at the floor of a 55gal.. Tannin stained water..


----------

