Making LED Illumination for Fish Aquariums

The discussed LED light circuit with timer was requested by Mr.Nikhil for illuminating his 4 x 2 feet fish aquarium. Let's learn more about the proposed circuit idea.

Technical Specifications:

"Hi Swagatam.....
i wanted to make a led lighting for my 4x2ft aquarium. i need at least 400 straw-hat led circuit each of 5mm. can you please design the circuit....

The Design:

The fish aquarium LED light with timer circuit  presented here utilizes a standard fish aquarium LED light set-up design for the required illuminations.

Two sets of LED colors are used, blue and white, which illuminate in tandem at an interval of 12 hours each. The switching is controlled through a simple IC 4060 timer circuit.

The white LEDs light up at 9 am and switch OFF at 9 pm, switching ON the blue LEDs. The blue LEDs remain illuminated from 9pm until 9am, when it's again replaced by the white LEDs....the cycle goes on as long as power remains available to the circuit. A standard ratio of 1:6 is used for the LEDs, i.e. around 348 white LEDs and about 51 blue LEDs.



Simulation and Working:

The diagram shows a simple circuit based upon the universal timer IC 4060 for implementing the sequencing operations of the involved LEDs.

The product of R2 and C1 determines the timing frequency, which must be set roughly for generating 12 hour intervals.

C1 may be taken as 0.68uF, while R2 may be appropriately selected for generating the above time frequency through some trial and error.A small value resistor say a 1K may be selected for R2 to check what time interval it generates, once we get this, the value for 12 hour may be easily calculated through cross multiplication..

If after a few days the time intervals seem to be drifting away from the set start/finish hours, the switch SW1 may be pressed for resetting the sequence.

If required this can be done every morning at 9am for implementing accurate switching of the LEDs, and for maintaining a natural feel inside the aquarium habitat.

Let's assume the circuit is switched ON at 9 in the morning. The output pin#3 of the IC initiates with a logic low and the timer starts counting.

The low at pin#3 keeps T1 switched OFF, this creates a high potential at the collector of T1 which instantly triggers T3/T2 illuminating the white LEDs.

The white LEDs remains illuminated for so long the timer counts, and the moment the set time lapses, the output of the IC goes high (after 12 hours), this instantly switches ON T1 and the associated blue LEDs and switches OFF T2/T3 and the white LEDs.The cycle repeats as long as the circuit remains powered.

C2 and C3 helps to illuminate the respective LED banks gently, in a cool fading manner.

Parts List

R1 = 2M2

R2/C1 = see text

R3 = 470 Ohms

R4 = 10K

R5 = 100K

T1,T3 = 8050

T2 = TIP122

C2/C3 = 470uF/25V

C4 = 1uF/25V

IC = 4060

SW1 = push to ON switch (push-button)

LEDs = Blue 51 nos, white 348 nos. (super bright, roughened at the surface through a grinder wheel)

LED Bank Connections

The white LED bank is made by connecting 116 nos. strings connected in parallel. Each string consists of 3 white LEds with a 150 Ohms resistor.
The blue LED bank is also made in the above fashion using 51 nos. blue LED strings in parallel.

Using High Watt LEDs and Drivers

The above design could be used for operating high watt LEDs with special 220V drivers, as shown below:

Note: Please add 2200uF/25V capacitor across the LED modules pins so that the switching transitions are seamless and not abrupt.

3 watt LED for aquarium timer light

Need Help? Please send your queries through Comments for quick replies!


  1. Hello Mr.Swagatam
    First of all I would like to appreciate all of the effort you have put into designing and describing in detail all these wonderful circuits in was also delighting to see that you have given quick replies to any comments posted.

    I have searched the internet a lot trying to find a 25w led driver for my planted aquarium but have failed to find a suitable design,
    The specifications that I look forward to from the led driver are as follows,
    1.Should be able to drive 25 1w white leds(Forward voltage(V): 3.2 - 3.6, Forward current: 350mA).
    2.Leds should be lit at maximum brightness.
    3.Parts involved in the design of the circuit should be easily sourced.
    4.I would also be great if it was possible to reduce its cost.

    Furthur information,
    I presently have a twin 18w fluorescent tube fixture without a reflector(which further reduces its useful light output),my aim is to somehow replace the existing setup with a led fixture with reduced power consumption whilst maintaining the same level(or higher level) of illumination.

    Could you please design a circuit for this requirment.
    Thank you,
    Sachintha Weerasinghe

  2. Thank you Sachintha, your requirement looks quite straightforward so it can be implemented easily.

    First you will need to procure a 12V 2 amp SMPS adapter unit, and connect its positive (+12V) to a current limiter stage as described in the first diagram of this article:

    once this is done, you'll need to connect the 25 LEDs across the output of this limiter stage and the ground line, in the following way:

    first make 6 strings of LEDs having 4 LEDs connected in series in each string.

    Then connect all these 6 strings in parallel with each other.

    Finally you can connect the common positive, and negative joints of these LED strings to the output of the current limiter.

    R1 for the current limiter can be selected as 0.7 ohms, 2 watt

    the Leds will need good heatsinking

  3. Hello Mr.Swagatam its me,Sachintha again,
    Thank you very much for the wonderful reply,it seems now that building the light for my aquarium isn't much of a problem after all.
    However I still have a query to be clarified,
    Would it be all right if I use a spare DELL laptop charger(19.5v 3.74amp) as the power supply instead of a 12v 2amp power supply.If this is possible would the output voltage of the current limiter circuit be 19.5v as well?

    Thank you.

  4. Hi Sachintha,

    yes definitely you can use the mentioned power supply, which makes the application even simpler:

    With 19V you can accommodate 6 LEDs on each string, and incorporate 4 such strings in parallel, with the output of the specified current limiter stage.

    and now R1 for the LM338 current limiter stage becomes 1 ohm/2 watt

  5. ....make sure the LEDs are mounted on a good heatsink and also the LM338 IC....

    you can associate the two heatsinks together (without physically touching them) for getting ultimate protection for the LEDs.

  6. Dear Mr. Swagatam,

    is it possible to add one more color to this circuit.
    i need the uv led as well for killing bacterias and for color improvement for fish and plants.
    second question ...can i use the led strips from aliexpress for this circuit.

    Thanks in advance.


  7. Hi Johan, could you please tell me how do you plan to keep the UV LEDs illuminated, because the two channels shown in the diagram are designed to operate alternately throughout the day.

    yes you can use any standard 12V LED strip and use it in the explained circuit idea.

  8. hi.
    thanks for the quick reply and sorry for the late reaction on your question.
    i was planning to leave the UV on to support the other leds because led light is not giving enough uv for plant grow.( this is told to me by a aquarium sales man)
    i think about 50 uv leds in cooperation with the others.
    I have made a PCB for this dimmer but i was missing the value of R5, this was not in the text or the parts list.
    Further i have another question for you, can i use another transistor for the 8050 because that thing is very difficult to find here, only aliexpress can deliver but that will take me 3 to 4 weeks before it is here.
    i hope you keep on the good work because you solved a lot of questions for this hobby group.



  9. Thanks Johan,

    OK in that case you can simply connect the UV leds with the supply lines, so that they remain illuminated always as long as power is ON.
    R5 can be any resistor between 10K and 1M
    instead of 8050 you ca try 2N2222 or any similar NPN BJT

  10. Hi.

    i am still waiting on the parts from aliexpress to build the dimmer.
    in the meantime i have another problem.
    I build a heating thermostat for my aquarium with a digital module but now i am looking for a schematic for a real fast switch that can switch to battery in case of a power failure.
    i try a simple circuit with a relay but that is not fast enough and the data got lost.
    you can imagine that in colder periods this will be lethal for my fish if the heating is off for a few hours.
    i hope that you can help me out here because i cant find anything in the stores over here.
    the thermostat works together with the dimmer so the temperature is also following a natural rhythm with the light.

    thanks in advance .


  11. Hi, you can try a triac instead of a relay, that will be much faster. I am assuming the heater to be an AC heater therefore I have suggested a triac.

  12. ...or you can tell me the specs of the system, I'll try to suggest a more feasible idea accordingly

  13. Hi.
    Yes the heater is AC but is controlled by the digital module that contains all the settings.
    as soon the power is cut from this module the data is gone and need to be programed again.
    i think you know that if this happens at night the temperature is dropping real fast and the fish can get a few diseases that can be fatal for them.
    what i am looking for is a digital solution that i can use to switched to a set of lithium ion (18650) batteries.
    i hope that you have a solution for me because i have looked for it a whole week and nothing found.


  14. Hi, OK got it, do you have any DC power option available for the module, if it is present then the changeover can be implemented through a simple DC circuit, please check whether or not the module has this feature, if not you can try opening the unit and create an outlet for enabling an external DC power connection.

  15. Hi.
    if i understand you well you mean that i should let the unit run from the batteries instead of AC power supply.
    that is not a bad idea but then i need a circuit that keeps the batteries loaded.
    i send you a schematic from the unit so you can tell me if this is possible with lithium ion batteries because normal batteries are not done i think.
    the module runs normally on 1.5 volt battery power but that is without the rest of the circuit as in relays and the switch circuit for the relays.
    what i want to do is building a 12 volt lithium ion power source and use a AC power source to keep the batteries fully loaded all the time.
    is this what you have in mind. ????
    how can i send the file with the schematic ???


  16. Hi, yes that will do, you can try the first circuit from this article

    if you are using a 12.6V Li-ion battery, set the zener diode at the transistor base in such a way that it produces precisely around 12.5V, this will keep the battery level just at the brink of getting fully charged, and prevent it from overcharging.

  17. Hi. Swag
    i am experimenting with the dimmer (the one with 1 4060) and i have a question about the illumination speed.
    the first sec it goes reasonably slow but as soon as it comes to 1/3 of the light strength then it goes like a rocket to full strength.
    what also looks strange is that the power in is 12volt as needed for the leds but the power out to the leds is no more than 10 volt.
    at that low voltage the leds use twice the amps as normal.
    is there something i could do about that.
    i already try higher values for C2 and C3 up to 4700uF but that makes no difference to the illumination flow.
    hope to hear from you soon.

    best regards : Johan.

  18. Hi Jason,

    getting 10V instead of 12V looks very strange, that should not happen, because the BJt's collector/emitter resistance is supposed to be negligible and allow full voltage across the LEDs, you can verify the same by replacing the BJT with a new one.

    To improve the dimming effect in the above design you can upgrade the transistor base R/C stage into multiple RC stages as shown in the last circuit from this article, it's called integrater.

    you may also need to upgrade T1 into a Darlington BJT, and additionally place the LEDs at the emitter arm of the transistor, and connect the collector directly with the positive line.
    I hope this helps

  19. Hi. Swag

    i try the changes you ware advising but this is still not giving me the result i wanted.
    i use the darlington transistor make more R/C configurations but the voltage stays at 10.5 volt to the leds by 12v input.
    also the blue channel is not going out completely and with the white leds powered on the voltage to the blue channel stays 9.1 volt.
    i made 3 more R/C units from 1000uF to 220uF but the illumination speed stays very high.
    i measured 2.6 seconds from off to full power and that is way to fast.
    my intention with this circuit was to make a sunrise simulator that gould follow the ritme of the real sun up with a delay of about 40 minutes to full power.
    my plan now is to make a timer switch with 8 to 10 channels so i can switch on the lights in 10 time frames with an interval of 4 to 6 minutes.
    if you can help me there your with an idea or a schematic then you make me very happy because me myself has not a clue how to do that.
    only thing i know for sure is that the switching needs to be done with transistors or triac.
    further i am curious to here from you if the guy that requested the dimmer was able to get it to work or that he is having the same problems a i have.
    we bothe has to use it the same way so that is why i am asking this.
    thanks for your effort on answer all my questions and i am awaiting your reaction.

    BTW from which country you are ???? my guess is india but i am not sure.
    i live in holland.

  20. Hi Jason, this circuit is too basic and simple and therefore has limitations, the fading will be ultimately dependent on the capacitor charging rate, so it may not be possible to get extremely long delays unless we try opamps, or CMOS IC.

    your second idea of switching the LEDs through a stepped manner looks good and will allow you to get the desired effect at the desired rate.

    you can try the following conept:

    adjust the IC 555 oscillator rate to get the desired timer interva for the fading or rising effect, also make sure to set the 10K preset correctly for getting the required slow transition effect.

    please note that, you will have to make an effort to first understand the concept and then proceed, otherwise you may find it any circuit hard to optimize, therefore I always advise the readers to first grasp the working of the circuit and then proceed with the construction, this will also give to power to troubleshoot the design yourself without my help, or even improve my circuit if there's a possibility.

    Yes I am from India, glad to meet you Json.

  21. Hi. Swag
    I have a big problem.
    As I told you I am building my aquarium light installation with timers.
    I choose the 24 hours 1 shot timer (no 2) from Ron’s website to do this.
    I build also the 24 hours (no 1) but have the same problem whit it.
    What I planning to do is to let the first timer switch power to the second and the second to the third enz.
    My problem is the following : when I switch light with the timers they work ok and do exactly what they have to do.
    When I let them switch on the other timer he resets and start all over again.
    I am fighting this problem for 1 week now and cannot solve it.
    I was thinking that the transistor can’t handle the power and interrupting the power signal to the relay.
    I hope that you can help me out and know what I am doing wrong.
    Or maybe you have a schematic for a one shot timer that don’t have these problems.
    A nice thing would be a timer with start delay till one hour and programmable for about 16 hours of running time and switch of after the programed run time.
    I am desperate because my aquarium is coming in 2 weeks and I am not even have way with the electronics.
    Hope you have a solution.
    Thanks in advance.


  22. Hi Johan,
    as per the following statement, I can suggest you a good timer circuit:

    "A nice thing would be a timer with start delay till one hour and programmable for about 16 hours of running time and switch of after the programed run time."

    Here is the link

    the upper section will allow you to get the 1 hour (adjustable) delay ON.
    the lower section will give you the facility of 16 hour (adjustable) delay OFF.

    but this will go on cycling forever.

    to get a one-shot OFF, you can ad a 1N4148 diode across pin#3 and pin#11 of the lower, exactly as done for the upper IC.

    hope this helps!

  23. Hi Mr.Swagatam,
    I would like to know if I can in-cooperate some 3W Leds and their Drivers into this circuit or maybe you can point me in the right direction (An Arduino Perhaps ?). I want to use 20 White and 5 Blue, they both have the same Specifications. Their Specifications are-:
    3W LED:
    Color:full spectrum
    Chip Brand:Bridgelux
    Lifespan:50000h lifespan
    Warranty:3 years
    lighting angle:120~140 degree

    Working temperature: -20-80 Deg
    Input Voltage: AC85V ~ 265V 50 / 60HZ
    Output Voltage: DC18V ~ 36V
    Output Current: 600mA
    TC: 75 degree (MAX)
    TA: 50 degree (MAX)
    Size: (L) 47mm * (W) 20mm * (H) 15mm
    Usage: Used for the 6 ~ 10pcs 3W LED Light

    Please guide me accordingly,

  24. Hi Garfield, I have updated the diagram for you, please see at the bottom of the article.

  25. Hi again Mr.Swagatam,
    Thank you for the speedy response. Correct me if I am wrong, in the above circuit, the Blue and White Leds are sharing the same Driver ? The Drivers can only support 6-10 Leds, therefor, I would be using Three (3) Drivers in total ( I may have to add one more Blue Led).

  26. Hi Garfield,

    The driver will not share the LEDs together rather alternately. Meaning only one of the LEDs will be handled by the driver at any instance. If you can explain me your requirement step wise then may be I can design a suitable version.

    Arduino is not yet within my field of expertise so I won't be able to suggest much.

  27. Hi again,
    Ok, I understand that. But what I am saying is that there are 20 White leds will be lighting at the same time, and the driver will only handle 10 LEDs at any given time. So what I need is to light 20 White leds with two drivers for 12 hours, then the 6 blue leds with 1 driver for 4 hours, Switching simitanusly. Thanks again.

  28. Hi, please tell me the specifications of all the LEDs, and your existing driver specification, I'll show you how to adjust them correctly in the last schematic without going overboard.

  29. Hi again,
    All specifications are all given in my first post. Thanks again.

  30. OK, I just forgot about it.

    Here's what you can do to adjust them in the last diagram.

    Use two drivers in parallel with separate diodes (1N5408) at their positive outputs. Adjust both the drivers at 36V full.

    For the white LEDs, make two strings of 10 LEDs, with 3 ohm 3 watt resistor on each string. Put both the strings in parallel and use it with one of the relay contacts.

    For the blue LEDs connect all the 5 in series, and use 26 ohm 20 watt resistor, and use this string with the other relay contact.

    If you want to avoid this resistor you can incorporate an LM317 voltage regulator adjusted at 16.5V for the blue string.

    Let me know if you have any doubts

  31. Hi again,
    Sorry for not responding sooner, I am at work on the sea. Will try the adjustment as soon as I can and get back to you. Thanks again for the great help.

  32. No problem Garfield, wish you all the best!


Post a Comment

 Follow on G+  Follow on Facebook   Follow on Tweeter  Follow on G+  Follow on G+

Follow Homemade Circuits