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tharsis 01-29-2012 07:48 PM

Retrofitting LED strip to T5 fixture - DONE! Post #13
I recently got a 36 LED dimmable kit from with a 16"x7" heatsink for my 20G reef tank (18 royal blue and 18 clear white 3W bridgelux LED's). I accidentally blew 7 of the blues through my own stupidity :icon_redf and instead of ordering new ones I decided to go a different route. I am splitting the kit up to make a freshwater light for my 10 Gallon shrimp tank (with the whites) and just supplement my T5 lighting with blues for my reef tank.

So here is the schematic for my freshwater set-up.

The outer rectangle is the tank footprint (10 gallon) and the inner is the heatsink footprint. It is 3" from the outer LED's to the edge of the tank. I am going to use 60degree optics and I plan on hanging it about 6" above the tank so ~18" from the substrate.

It has a maxwellen dimmable driver so I can dial in the amount of light. They will all be 10000K clear white, I like the higher kelvin look of the 10000K in my FW tanks anyways so this should be ok aesthetically speaking. I just hope that the spectrum is ok for plant growth ...

I would also like to build an enclosure for it to give a cleaner look...but I will have to do some research for that.


This is what I am planning with the reef tank (Starts @ post#8):

It is a 4 bulb T5HO Odyssea fixture and I will add 14 LEDS (9 blues and 5 whites) on a strip attached to a dimmable driver as well. I have no idea how I will do this yet though :)

I am thinking a hollow aluminum square tube as the heatsink and then figure out a way to have it swivel on an axis parallel to the long dimension of the fixture. This would allow me to change the angle of the LED's to change the position of the centre line hitting the rock (not sure if that made sense...I will have to get a diagram).

So anyways... I will document the progress of both lights here!

Hoppy 01-29-2012 11:56 PM

That is likely to be way more light than you will want, possibly so much the dimmer will not be able to reduce it enough. I think I would just use one row of 5 LEDs. I'm not sure you will gain much from using the optics either.

tharsis 01-30-2012 12:50 AM

Thanks for the input! I figured it would be alot of light and likely overdoing it, but are you basing that on Crees? The Bridgelux don't have as much oomph as the Cree LED's from what I have read. What kind of PAR values would 5 Crees vs 5 Bridgelux have at the substrate?

Bottom line is that I have to go with atleast 12 LEDS because the driver I have is for 12-20 LEDS. With this in mind, my rationale for it being doable is that:

1)the bridgelux don't produce as much PAR as the Crees
2)I can dim the fixture
3)I can raise the light as high as I want

In terms of first hand experience, I have been playing around with the fixture (32 LED's) for the last couple of weeks over my reef tank and the dimmers do quite a remarkable the lowest setting my mushrooms would start reaching up for the light which never happened with my 4bulb T5HO odyssea fixture. This suggests to me that the light level for 32 Bridgelux LEDs (dimmed to the minimum) is less than the T5 4 bulb fixture. I am currently running 2 T5 bulbs (Odyssea) over my shrimp tank with no problems so 13 Bridgelux LEDS dimmed to the minimum should be less than the 2 bulb fixture.

Alot of assumptions I know...but my goal is too have a highly versatile fixture that will be usable over a wide range of tank sizes and light levels. If it proves to be way too much light, I can order a new driver and take out some LED's...or get a bigger tank for it haha.

Hoppy 01-30-2012 08:15 PM

I based my comment on my gut feeling from playing with LED lights, including cheap Ebay 1 and 3 watt LEDs. Since I have no data for the Bridgelux LEDs, I'm not sure just how much light you would get. I am 80% sure it will be way too much with all of those LEDs on, at even 200 mAmps. If you are willing to raise the light a foot or so, then it should work ok, but then you have to provide a glare shield to keep the LEDs from "blinding" everyone in the same room with it. You can rivet aluminum angles, or strips around the heatsink to act as shields.

tharsis 01-31-2012 04:01 AM

Thanks for the interest in the build Hoppy. I guess I will be a guinea pig for these LED's in a planted tank.

I soldered everything and have it set up already. Here are some pics:

90 degree optics installed

lowest setting

highest setting:

above of the tank (~1.5 feet above tank) with no shield:

with shield

close up of makeshift light shield and fan, I took apart an odyssea 20" fixture and plan on rebuilding it to make the enclosue for the heatsink

tharsis 01-31-2012 04:04 AM

Example of dimming same camera settings for all pics:

lowest setting-

pic of the driver and potentiometer

FishermansDwarf 01-31-2012 05:31 AM

Looks good!
I got two of the 24 LED sets with mostly 6500K some 10000k. Nice color
This is my first time using LEDs and I am impressed. They are really bright but can be dimmed down a lot.
I will be hanging them over a Oceanic Illuminata.

tharsis 02-02-2012 01:03 PM

Thanks! Good luck with you build.

I am ready to move on to phase two, which involves adding a strip of LED's to my existing T5HO fixture for my saltwater tank.

This is what I am thinking of doing:

I think that square aluminum tubing should be good for a heatsink...something like this:

I can screw the struts to the side of the fixture and then I just need to find a way to attach the heatsink to the struts so that it can rotate. This will allow me to 'point' my leds where I want them depending on the height of the fixture.

I am going to wander around lowes today looking for some inspiration but if anyone has any ideas please share!

tharsis 02-04-2012 10:10 PM

Alright well I think that this will be easier than I thought. I just did a quick proof of concept here.

Here are my starting materials:

Attached L-bracket to a straight bracket. It is tight but the angle is adjustable

I am going to drill holes in the square tube and then screw the brackets to that.

For now I am just duct taping it to see how it works.

Attached together

rotated to adjust the angle of the LEDS

Duct taped to my light fixture (again temporary)

I will screw it into the side of the fixture. There is enough room on the ends to allow for a nut and screw. The whole unit is very light weight so it shouldn't put too much stress on the plastic.

Close up of the angle of the bar

example with 60 degree optics

I may bring the brackets out a bit more to limit light hitting the top of the fixture. I think I will paint the whole thing black so that it blends in with the fixture.

So it is almost ready for the LEDs!

This is a super easy retrofit, it is light weight and cheap ~ $15 in materials.

tharsis 02-05-2012 05:15 AM

Alright, got it painted and screwed, I am quite pleased with it. I couldn't find any drill bits for attaching the L-bracket to the heatsink so I just crazy glued it and then wrapped it with duct tape. Screwing it would have been more professional but it is really solid and and I am not too worried about it.

Amazingly, the holes on the bracket lined up perfectly with the screws in the fixture so I didn't have to drill anything.

Now I just need to add in the LEDS and the wire them up and its all done! It should be up and running tomorrow.

diwu13 02-05-2012 06:45 AM

Great job tharsis. Did you paint over the duct tape as well? Do you have to loosen the screws on either end to adjust the angle? Or is there just enough of wiggle room?

tharsis 02-05-2012 02:09 PM

Thanks Di. I did paint over the duct tape, I wish I had waited to find my drill bits but I just wanted to get it assembled and painted last night so I could add the LEDS today.

My initial plan for swiveling the light bar was to have a couple fasteners with wing nuts that I would loosen. But I tried it with the screw and nuts first and it works really well. It is tight enough that the bar stays fixed, but it is loose enough to be able to adjust it without unscrewing it. I think with time it will loosen on its own and have to be re-tightened , but I don't plan on fussing with it too much. Once I get the angle of light that I like I will just leave it be.

tharsis 02-06-2012 12:54 PM

Done! Finished it late last night.

Added some electrical tape to the 60 degree optics because they were clear housing

Obligatory pic of them on:

Attached to the fixture

Facing the right way

On the tank:

I haven't tested them out yet, looking forward to try them out when I get home from work. I am probably going to have to raise the fixture up to avoid any spotlighting. I am also wondering if I will need a fan... time to gut my old pc.

monkeyruler90 02-06-2012 07:22 PM

looks great. very professional!

tharsis 02-08-2012 04:08 PM

Thanks bud!

It is working like a charm! It gets a little warm when the lights are cranked full blast so I will need to get a couple fans but for now I am only running them at 50% so no problemo.

I don't know if I will ever run it at full blast though, it is wicked bright with the T5's and the LEDS at full.

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