Light Frame Actuator For Open Top Aquariums (diy)
The design and mounting of the lights over my open top tank was a challenge faced with a number of options available, legs attached to the light, hang from the ceiling or build a support coming over the back of the tank or hiding everything in a hood. Having originally done a height adjustable light over my 2’ nano tank many years ago thought I would upscale this concept to support my 18kg ! ATI T5 PowerModule.
Design Goal:
With the location of the tank & the size of the room I did not want the apparent bulk of a hood hiding the lights. Thus something sleek and provide the illusion of the light hovering over the tank.
Frame Material: Without easy access to a welder I opted for 40mm T-Slot aluminium extrusion. There are a few brands however I used the “Item” brand, a German product with a distributor in Dandenong Victoria. The great thing about T-Slot is its super strong, can create a 90 angles and with the T-Slot nuts join/attach anything down its length. I used this for the light frame and also matched it into the front supports of the tank cabinet as well. The distributor also cuts this to length so with careful design you don’t have to cut anything, and its all square.
40mm T-Slot aluminium frame
Rails: I purchased some heavy duty draw slides, 400mm length @ 60kg. Although they are mounted vertically the weight of the light is trying to pull the frame over the top of the tank. Thus the force on the rails is still against the bearings.
Draw rails attached to 3mm aluminium angle bracket
Actuator: A linear actuator is used a lot in home automation for opening windows etc. Its rated at 300 mm stroke @ 50kg. It has a small 12VDC or 24VDC motor which is mounted within the unit itself. Internal limit switches within the actuator stop it burning itself out when it hits both extremes of its travel. Extending or contracting simply relies on reversing the motor wiring. In its simplest form a normal switch (DPDT) can be wired to the actuator and a 12VDC supply to raise or lower the unit.
Feedback of light position to a controller : You could also optionally use a linear potentiometer to tell a controller where the light is at any point in its travel. That way a controller (Arduino / RPi) could raise or lower the light automatically during the day or for instance have a maintenance program set where the light simply raises to its max height. I purchased the potentiometer however did not end up installing this feature. I just have a two position rocker swicth and send it up or down. Takes about <10 sec to travel 300mm
Linear 10k potentiometer 300mm long
Good Points: :)
Bad Points: :(
Additional features on the list for 2014/2015 :
I now have a DIY LED over the tank. This is a lot thinner than the Powermodule so do not use the actuator so much, as I can clean the glass with the light in place. The arms of the stand are more suited to a 18kg powermodule. I want to move both the arms into the middle of the tank and have both arms maybe 30 cm part, instead of as it is now at either end of the tank. These arms not over the top however direct connected to the LED heatsink. This would allow me to meet my initially idea of creating a light that hovers over the tank...
Note to myself ....Need to post a PIC of the new LED unit
Final thoughts:
It would be very difficult having a hood-less tank where I had to lift off or push backwards the light having had this on my last two tanks. Although now with the smaller lights I don’t use it very often it does make the chore of tank cleaning or adding coral just that little bit easier.
Rear 3d Sketchup of the plan
Design Goal:
With the location of the tank & the size of the room I did not want the apparent bulk of a hood hiding the lights. Thus something sleek and provide the illusion of the light hovering over the tank.
Frame Material: Without easy access to a welder I opted for 40mm T-Slot aluminium extrusion. There are a few brands however I used the “Item” brand, a German product with a distributor in Dandenong Victoria. The great thing about T-Slot is its super strong, can create a 90 angles and with the T-Slot nuts join/attach anything down its length. I used this for the light frame and also matched it into the front supports of the tank cabinet as well. The distributor also cuts this to length so with careful design you don’t have to cut anything, and its all square.
40mm T-Slot aluminium frame
Rails: I purchased some heavy duty draw slides, 400mm length @ 60kg. Although they are mounted vertically the weight of the light is trying to pull the frame over the top of the tank. Thus the force on the rails is still against the bearings.
Draw rails attached to 3mm aluminium angle bracket
Actuator: A linear actuator is used a lot in home automation for opening windows etc. Its rated at 300 mm stroke @ 50kg. It has a small 12VDC or 24VDC motor which is mounted within the unit itself. Internal limit switches within the actuator stop it burning itself out when it hits both extremes of its travel. Extending or contracting simply relies on reversing the motor wiring. In its simplest form a normal switch (DPDT) can be wired to the actuator and a 12VDC supply to raise or lower the unit.
12VDC Actuator 50kg lift in the middle of the frame
Feedback of light position to a controller : You could also optionally use a linear potentiometer to tell a controller where the light is at any point in its travel. That way a controller (Arduino / RPi) could raise or lower the light automatically during the day or for instance have a maintenance program set where the light simply raises to its max height. I purchased the potentiometer however did not end up installing this feature. I just have a two position rocker swicth and send it up or down. Takes about <10 sec to travel 300mm
Linear 10k potentiometer 300mm long
Good Points: :)
- When I had the ATI T5 taking up 90% of the top area of the DT, simply raise the light for glass cleaning or to get something out of the aquarium. No more dripping lights or managing power cords when lifting off. This was the #1 winner if you have a wide x deep light such as a T5 powermodule.
- Could change the T5 tubes and just run the light 8” higher for 2 weeks then slowly bring it back down, beats changing one tube at a time.
- It was a cool feature to show people it goes up & down….. !
- Can take the weight of what is very heavy light fixtures.
- "Item" T-Slot has a great finish and has never seen any corrosion.
- You can easily attach cooling fans to the rear of the light fixtures without having to attach to the back of the tank or top brace.
Bad Points: :(
- Limits the tank plumbing at the rear of the tank, as the frame has to be able to go up/down without hitting any fittings. I have my plumbing at either end of the rear of the aquarium.
- You need to brace the back of the cabinet where the unit mounts. With the ATI powermodule the whole assembly weighed ~25 kg.
- the 40mm T-Slot looks like robot arms now I'm using a smaller narrower LED fixture. (design change on the cards, see below)
Additional features on the list for 2014/2015 :
I now have a DIY LED over the tank. This is a lot thinner than the Powermodule so do not use the actuator so much, as I can clean the glass with the light in place. The arms of the stand are more suited to a 18kg powermodule. I want to move both the arms into the middle of the tank and have both arms maybe 30 cm part, instead of as it is now at either end of the tank. These arms not over the top however direct connected to the LED heatsink. This would allow me to meet my initially idea of creating a light that hovers over the tank...
Note to myself ....Need to post a PIC of the new LED unit
Final thoughts:
It would be very difficult having a hood-less tank where I had to lift off or push backwards the light having had this on my last two tanks. Although now with the smaller lights I don’t use it very often it does make the chore of tank cleaning or adding coral just that little bit easier.
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