How Many 3W LEDs for low tech 55? - The Planted Tank Forum
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post #1 of 54 (permalink) Old 05-28-2017, 09:07 PM Thread Starter
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How Many 3W LEDs for low tech 55?

Hello,

I am upgrading the Aqueon Deluxe Flourescent Hoods that came with my new 50gallon (48" x 12" x 19") tank. The plan is to remove the flourescent internals and build the heat sink and fans into the enclosures. The led driver will be attached to the back of the housing.

I need guidance in estimating how many 3W leds I will need for this low tech planted tank.

The plan is to move the plants from my 29 into the 50. It has Amazon Swords (have grown to about 15"), Hygrophilia, Lugwigia Repens, and Creeping Jenny, all of which were doing well until the DIY Led strip lights started to burn out and yellow. Now there is alot of green algae and stem plants arent doing great anymore. Tank is sand over soil, Co2 Booster, root tabs, Leaf Zone.

I think these are easy medium light plants and I don't plan to do anything more difficult. The growth was steady without CO2, so I'm looking for light that is in the sweet spot -- good enough to grow, but doesnt need CO2. Nothing against CO2 setups and I will do one eventually, just not yet.

My 29 is/was lit with roughly 1.5 ledmo 6000K 3650 strips..roughly 90 watts. Was lit pretty well.


Guessing that I will need 30x 3W Leds. Mostly white with some blue and red. Opinions?
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post #2 of 54 (permalink) Old 05-29-2017, 02:51 AM
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largest dim. is usually 1st.
did you mean 5630's?

Using smd strips your wattage is usually system watts and not exactly comparable to 3w constant currrent.

Anyways..any game plan for automation?

"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 54 (permalink) Old 05-29-2017, 01:44 PM Thread Starter
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Yeah, opps type. They are 5630s.

I was wondering about automation. If I get drivers with a dimmable input, then theoretically there is probably some controller that would allow me to automate the cycle. Is that really necessary? I use a wall timer with two on periods and a siesta. I have an RGB strip on separate power that I can add for color enhancement or moonlight.

So, how many 3W LEDS for a 55g? I'm thinking 32. Should I go all 6500K, or mix in some red/blue? I know I can get fancy with multiple drivers, but this is just low tech.

Bump: Also, is there a way to get rid of ad streaming on this site? It really messes up the forum functions; keystrokes are lagging and missed. I cant see myself using this site much because of all the lagging and blocking from the ads.
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post #4 of 54 (permalink) Old 05-29-2017, 03:21 PM
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I happen to think dimming is a necessity...
Esp if you use 32 3W emitters on a 55gal.

automation (ramp up/down multi-channel) isn't but it can be relatively cheap w/ some solder-equity

There are numerous ways to approach this and tech changes all the time.
suggest looking at these constant current Bridgelux EB strips for a retrofit..
11", 22" or 44" 1" wide..
Should be able to pack at least 3 per "bay" @ 22".. You need to check your room. 15W 2400 lumens per 22" strip @ 700mA

LED Build, 465 Watts (Bridgelux EB Strip LEDs, prev. Vero18) *Updated 2017-01-18*
Easy to get a 2 channel design (cool white/warm white)

Short list:
Strips
Power supply (24V 6A for 6 EB strips)
LED drivers w/ 5V pwm (3 minimum @ @ $8 each)
dimmers or programmer ($9 to $40 w/ some solder skill to mod off the shelf parts. See How to use TC-420 to control Ldd drivers

As to "wattage" well that is a bit tricky due to efficiencies/in-efficiencies of LED brands/styles
Personally anything over 30W needs some "control"..
90W can translate into the old 3W/gallon thinking..but depends on efficiency of emitters..
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Last edited by jeffkrol; 05-29-2017 at 03:30 PM. Reason: edit
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post #5 of 54 (permalink) Old 05-29-2017, 03:44 PM Thread Starter
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Thanks. As far as dimming, I was planning a really low tech solution which is to put a grate between the lights and glass.

For instance bug screening or chicken wire. AFAIK that would reduce intensity by some %, and it could be adjusted based upon quantity/type of material. I could simply put thin strips of tape across glass. Or I could remove leds if the driver isn't too large.

This way if I ever get CO2, I can just remove the filter.

Ive decided to use a mix of cool white and warm white. Can someone recommend a good ratio of cool to warm?

I'm thinking 70% cool, 30% warm.

Quote:
Originally Posted by jeffkrol View Post
I happen to think dimming is a necessity...
Esp if you use 32 3W emitters on a 55gal.

automation (ramp up/down multi-channel) isn't but it can be relatively cheap w/ some solder-equity

There are numerous ways to approach this and tech changes all the time.
suggest looking at these constant current Bridgelux EB strips for a retrofit..
11", 22" or 44" 1" wide..
Should be able to pack at least 3 per "bay" @ 22".. You need to check your room. 15W 2400 lumens per 22" strip @ 700mA

LED Build, 465 Watts (Bridgelux EB Strip LEDs, prev. Vero18) *Updated 2017-01-18*
Easy to get a 2 channel design (cool white/warm white)

Short list:
Strips
Power supply (24V 6A for 6 EB strips)
LED drivers w/ 5V pwm (3 minimum @ @ $8 each)
dimmers or programmer ($9 to $40 w/ some solder skill to mod off the shelf parts. See How to use TC-420 to control Ldd drivers

As to "wattage" well that is a bit tricky due to efficiencies/in-efficiencies of LED brands/styles
Personally anything over 30W needs some "control"..
90W can translate into the old 3W/gallon thinking..but depends on efficiency of emitters..
Reading this again, took some time to sink in.

I was leaning towards AC input driver so I can use the switch/plug and internals already built into hood. Just a very basic on/off operation. Color balance made based on LED ratios, not using separate banks.

Leaning away from DC because would require separate power supply as well a driver, (and more hacking of the encasement) but I know it is much more functional.

I already have 2x 60W (12V) unregulated power supplies. If I could reuse these with CCD, I would be interested, but I would need to know how to wire the 3K LEDS. I think I would need a CCD that could raise the voltage, because 12V at a fixed 600mA wouldnt light many leds.

BTW, there are 2x 22" light bars being retrofit. So I was planning on a single channel for each bar with a 70/30 mix of cool white / warm white each. What kind of drivers would I need to reuse the 60Watt power bricks I own?

Last edited by Darkblade48; 05-30-2017 at 02:59 AM. Reason: Please use the edit function for back to back posts
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post #6 of 54 (permalink) Old 05-29-2017, 10:14 PM
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Quote:
Originally Posted by ChrisX View Post
Ive decided to use a mix of cool white and warm white. Can someone recommend a good ratio of cool to warm?

I'm thinking 70% cool, 30% warm.
Fairly standard, you can play a bit w/ this:
SPECTRA

Quote:
Originally Posted by ChrisX View Post
Reading this again, took some time to sink in.

I was leaning towards AC input driver so I can use the switch/plug and internals already built into hood. Just a very basic on/off operation. Color balance made based on LED ratios, not using separate banks.

Leaning away from DC because would require separate power supply as well a driver, (and more hacking of the encasement) but I know it is much more functional.

I already have 2x 60W (12V) unregulated power supplies. If I could reuse these with CCD, I would be interested, but I would need to know how to wire the 3K LEDS. I think I would need a CCD that could raise the voltage, because 12V at a fixed 600mA wouldnt light many leds.

BTW, there are 2x 22" light bars being retrofit. So I was planning on a single channel for each bar with a 70/30 mix of cool white / warm white each. What kind of drivers would I need to reuse the 60Watt power bricks I own?
Generally switching power supplies are used..Bit less critical w/ constant current drivers but a bit necessary w/ things like strips that run constant voltage.
Voltage variations will run havoc on output and longevity..
LED series parallel array wizard

this will give you an idea what you can or cannot do ..
It's for designing constant voltage strips using resistors as "current regulators"..
3W diode forward voltage varies from 2-4v.. Using 3.7 for cheapp 3w diodes will keep you in the ballpark.
Note voltage changes w/ current fed.. well the higher the voltage the higher the current the LED will use..
too much voltage and it goes into thermal runaway and frys out..

constant current or constant voltage your V9f) is still key..


your ps are capable of 5A..

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

Last edited by Darkblade48; 05-30-2017 at 02:59 AM. Reason: Please use the edit function for back to back posts
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post #7 of 54 (permalink) Old 05-29-2017, 10:54 PM Thread Starter
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Quote:
Originally Posted by jeffkrol View Post
Generally switching power supplies are used..Bit less critical w/ constant current drivers but a bit necessary w/ things like strips that run constant voltage.
Voltage variations will run havoc on output and longevity..
LED series parallel array wizard

this will give you an idea what you can or cannot do ..
It's for designing constant voltage strips using resistors as "current regulators"..
3W diode forward voltage varies from 2-4v.. Using 3.7 for cheapp 3w diodes will keep you in the ballpark.
Note voltage changes w/ current fed.. well the higher the voltage the higher the current the LED will use..
too much voltage and it goes into thermal runaway and frys out..

constant current or constant voltage your V9f) is still key..


your ps are capable of 5A..
So cool, thanks so much! I suspected there was a series/parallel organization that would let me use the 12V supplies.

Just so I'm clear, in this configuration, would I need a constant current driver or could I connect to power directly?

If this works directly from switching power supply (converted computer PS), it unlocks potential for some really inexpensive (and scaleable) arrays. But would they also work from my bricks?

BTW, I believe the quality of my LED strips (first endeavor in DIY lighting) degraded because of unregulated supplies and poor power. If I am to understand, if I were to have used a switching supply with those strips, they would have lasted much longer?
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post #8 of 54 (permalink) Old 05-29-2017, 11:32 PM
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Quote:
Originally Posted by ChrisX View Post
So cool, thanks so much! I suspected there was a series/parallel organization that would let me use the 12V supplies.

Just so I'm clear, in this configuration, would I need a constant current driver or could I connect to power directly?

If this works directly from switching power supply (converted computer PS), it unlocks potential for some really inexpensive (and scaleable) arrays. But would they also work from my bricks?
As long as you add the resistors yea it works for larger diodes/arrays..
not as efficient as constant current.. See waste heat on the resistors.
substituting Meanwell LDDs for a resistor adds $7/ 3 diodes at 12V..


Quote:
Originally Posted by ChrisX View Post
BTW, I believe the quality of my LED strips (first endeavor in DIY lighting) degraded because of unregulated supplies and poor power. If I am to understand, if I were to have used a switching supply with those strips, they would have lasted much longer?
Possibly.. They also have poor thermal management and heat is the enemy

"A man with a watch knows what time it is. A man with two watches is never sure."
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post #9 of 54 (permalink) Old 05-29-2017, 11:44 PM Thread Starter
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Quote:
Originally Posted by jeffkrol View Post
As long as you add the resistors yea it works for larger diodes/arrays..
not as efficient as constant current.. See waste heat on the resistors.
substituting Meanwell LDDs for a resistor adds $7/ 3 diodes at 12V..
Given the above diagram, would it be possible to use my 60W power brick and a single LDD? How would it be wired?

It sounds like what you are saying is that each resistor would be replaced with a LDD, which would not be cost effective. Either I would need a higher Voltage supply, or multiple LDDs. (?)

What would be the effect of just powering that circuit with the 60W brick? It is rated at 12V (I would need to check actual voltage), but I suspect V drops very significantly as current draw rises, so as I add more LEDs, each one would have less intensity. I don't want that!

Alternatively, I could convert an old 400W computer power supply and power that circuit directly.

This is a budget build (for now). I could geek out (and may later), but I just want a basic low/medium light setup for a low tech 50g.

BTW, the resistors in that diagram, what power rating would they need?
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post #10 of 54 (permalink) Old 05-30-2017, 05:29 AM
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Quote:
Originally Posted by ChrisX View Post
Given the above diagram, would it be possible to use my 60W power brick and a single LDD? How would it be wired?

It sounds like what you are saying is that each resistor would be replaced with a LDD, which would not be cost effective. Either I would need a higher Voltage supply, or multiple LDDs. (?)
power supply to driver ..driver out to LED's.
Voltage of the power supply determines # of diodes you can drive.. Add V(f) up..
Also note LDD's require a voltage differential of 2-3V...
In other words if you have a 12V power supply and run LDD's you effectively only can output 10V..
I really don't recommend under 24V ps for Ldd's that is cost ineffective.. 24-2= 22
22/3.7 = 5 and possibly 6 (depends on the diodes and drive current) in series is more cost effective..
Quote:
Originally Posted by ChrisX View Post
What would be the effect of just powering that circuit with the 60W brick? It is rated at 12V (I would need to check actual voltage), but I suspect V drops very significantly as current draw rises, so as I add more LEDs, each one would have less intensity. I don't want that!

Alternatively, I could convert an old 400W computer power supply and power that circuit directly.

This is a budget build (for now). I could geek out (and may later), but I just want a basic low/medium light setup for a low tech 50g.

BTW, the resistors in that diagram, what power rating would they need?
resistors would need to be rated at 1W or better..All data is listed..
Calculator seems to assume 2x actual or better so 2W is minimum.
computer power supply could probably run 30 3w diodes
At say 500mA you would have an array of 3 in series x 10 rows.
Each row terminated w/ a 1W resistor @ 1.8Ohms..
https://www.amazon.com/1-8-Ohm-Flame.../dp/B008EM16D6

all are estimates
and you need to be aware that you can't mix V(f)'s. All diodes should have roughly the same forward voltage..

so generally no red diodes allowed .. though if you wanted some red you could use "full spectrum" 3w diodes which are really blue w/ heavy red emitting phosphors added.. Overall color is magenta..

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post #11 of 54 (permalink) Old 05-30-2017, 02:30 PM Thread Starter
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My concern about using an array with a 12V supply: What if one of the LEDs burns out? That could cause failure of the entire array.

The obvious benefit of using constant current; everything can be wired in series and if one burns out, it doesnt affect the others.

Here is another option, a Voltage booster with trimpot adjustment.
https://www.amazon.com/GERI-Constant...nstant+voltage

I could use this to create a constant (15V)voltage and use my power bricks. It would also allow me to adjust intensity with trimpot.

Tell me, if one of the LEDs burns out in constant voltage array, will the whole circuit fry? If so, I will go with a constant current setup.





Seriously, is there a way to disable the streaming ads on this site? I can barely type because of interrupts. Site is constantly reloading/blinking and blocking user input.

jeffkrol,

Thanks for your help. I decided to "keep it simple" and ordered a package of Ebay 3W LEDs and AC input CCDs, which I will retrofit into the flourescent hoods. The LEDS will be in a 70/30 ratio of cool/warm white, and the CCDs can handle somewhere between 8 and 16 LEDS, so I will control light intensity by the number of LEDS installed. Light cycle will be handled by external timer and supplemented with led strips I already have.

Now, I need to figure out a way to have small DC fans wired into circuit for cooling. Any suggestions?

Last edited by Darkblade48; 05-31-2017 at 06:36 AM. Reason: Please use the edit function for back to back posts
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post #12 of 54 (permalink) Old 05-30-2017, 04:52 PM
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Quote:
My concern about using an array with a 12V supply: What if one of the LEDs burns out? That could cause failure of the entire array.
no, just the triplet row.. all other 9 parallel channels will run fine..

Where one runs into problems is if you series/parallel off one constant current driver..
Say you have 2 parallel branches running off a 1A constant current driver..
Effectively each branch "sees" 500mA.
If one branch goes "open" all 1A will now go to the remaining branch..
So normally 1 driver-1 series string prevails with constant current..

Series/parallel constant voltage doesn't have that issue..
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post #13 of 54 (permalink) Old 05-30-2017, 07:29 PM Thread Starter
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Quote:
Originally Posted by jeffkrol View Post
no, just the triplet row.. all other 9 parallel channels will run fine..

Where one runs into problems is if you series/parallel off one constant current driver..
Say you have 2 parallel branches running off a 1A constant current driver..
Effectively each branch "sees" 500mA.
If one branch goes "open" all 1A will now go to the remaining branch..
So normally 1 driver-1 series string prevails with constant current..

Series/parallel constant voltage doesn't have that issue..
It turns out that the parallel resistors cost about the same as the constant current driver. While that could be a great strategy for someone who already has the power supplies and resistors, its not cost effective and adds to the complexity of the circuit. (And as mentioned, you lose one, you lose the row.) Also, my supplies are not regulated and would benefit from the Voltage regulator, which again adds to the cost.

I would have liked ability to dim certain LEDS, but thats getting fancy for little benefit at this point. With the CCD I can just add/remove LEDs and change ratios of whites. Will be fine for my low tech build.

Thanks again! I'm sure I will be back with updates/questions sometime in the next week as I retrofit my lights. This build will help prove the cost effectiveness/reliability of budget ebay builds. (I may have to start over.. but this is only $40 in components and should give between 50-100 Watts total, efficiency unknown, but I'm gambling it will be enough.)
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post #14 of 54 (permalink) Old 06-09-2017, 05:28 PM Thread Starter
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I got my LED shipment. They are "epistar" brand. I'm sure they are not in the same ballpark as cree, but I'm hopeful. Using inexpensive LEDs will let me experiement with different colors.

The specs are as listed:



The drivers were also purchased from this seller, they say they are 600 mA constant current, 60Watt. Out Voltage: 54-105V It says 18-30 x 2(3)w. That is kinda vague.

If the drivers forward voltage is 3.2-3.4V @ 700 mA, what is the forward voltage at 600? (Is it * 6/7) Are these effectively 2.*V at 600?

I am trying to decide how many or how few I can run from each driver.
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post #15 of 54 (permalink) Old 06-09-2017, 06:08 PM
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at 600ma your going to be arround 3.3 volts prolly so the listed number of diodes for the voltages your driver supports is correct. anywhere from 18-30 will be fine.
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