DIY diffusers for LEDs

[EMeyer]

Many have complained about disco ball effects and hot spots with black box LEDs. Like many, I've experimented with using diffusers to reduce this. I'm not satisfied with how its gone and am wondering if anyone else has found a better solution.

I've tried the plastic sheets sold at Home Depot for diffusing fluorescent fixtures. This gave about 30% reduction in PAR but produced a visibly more even spread without major hotspots. After turning them up to overcome the reduced PAR things looked good. It was promising enough to run them that way for nearly a year before finally admitting it was not helping. Many corals went downhill and grow was reduced overall.

Plastic is optically not a good choice, since it absorbs some wavelengths more than glass and especially as it ages. My theory is that the plastic diffusers were making the spectrum worse for corals.

I'd like to try a glass diffuser but cant find any easy materials for DIY. Privacy glass would be good, frosted glass might work too. Has anyone tried anything like this?

 

[Jacked Reefer]

Home Depot diffusers are not the most effective. I would get a piece of frosted acrylic and mount it about an inch or two away from the light.. the issues with frosted glass is mounting it. I see no way you could without a canopy.

 

[dantimdad]

Working on a frosted glass mount.

I wanted to try several different materials. When I get it down pat, I will post my steps to doing it.

It will work for all materials if it pans out.

 

[EMeyer]

I dont understand the difficulty with frosted glass. Why not just replace the glass panel of the black box directly with frosted glass? If I could find any that is what I would try.

 

[dantimdad]

I thought about it. IMO, diffusers work better a little farther from the LEDs especially if you have lenses on them.

I removed almost all the lenses on mine but still want about 1.5 to 2" from the actual bulbs.

 

[EMeyer]

I've removed lenses from the LEDs on my shallow frag tank. It gives me maximal spread and minimal hotspots, and still has plenty of PAR to penetrate the ~6-8" of water in that tank.

On deeper tanks, I've found that removing lenses makes it impossible to get decent PAR (>300).

I have read that its ideal to put diffusers far from the light but its so impractical. If I can find frosted glass anywhere I'm gonna try replacing the clear glass with it.

 

[dantimdad]

Actually, look at flippers 4 pups tank.

He removed the lenses. Fantastic growth and PAR

 

[redfishbluefish]

Why not try clear acrylic and use sandpaper to sand it. I'd start with 400 or 320 grit. If that doesn't give you enough "frosting", sand the other side.

If you still wish to use glass, sandblasting with "frost" the glass.

 

[dantimdad]

That's one of them I am trying. Just using several different grits on different pieces.

 

[Saveafish]

No no no. Take all the lenses OFF. Than get egg crate. Don't use the frosted sheet panel. I did it. I'll post pics.

 

[Saveafish]

F

Here.

 

[dantimdad]

I'm not following how the eggcrate can help with hotspots and blending.

Not arguing. I curious. I want to come up with the best solution for diffusing these things.

 

[Saveafish]

I'm not following how the eggcrate can help with hotspots and blending.

Not arguing. I curious. I want to come up with the best solution for diffusing these things.

This was my try and fails. With the lenses it made hot spots. Without lenses it was too wide of a spread. The egg crate seems to be in the middle. It was by accident I found it out. I used one to hold my light on my rack while I was tinkering and saw such a good spread. I was darn here we go. I'm loving it. I was also able to lower them closer to the tank as well.
I'm thinking it defuses the light lower under the LEDs, causing a mixed spread.

 

[dantimdad]

ok, well, if have eggcrate laying around, it won't hurt to try it too.

So now, I have 6 different grits of sanded plexi, prismatic plastic and will add the eggcrate to the mix.

Can't wait to get testing this.

 

[Saveafish]

Yea test day.

 

[Thingsibuild]

I'm wondering how it works also.

 

[Saveafish]

Angles?
http://lowel.tiffen.com/edu/light_controls/egg_crates.html

 

[Lingwendil]

Why not use the acrylic that is intended specifically for light diffusion?

https://www.acrylite.co/acrylic-products/sheet/diffusion-grade-satin-ice.html

I've used it on a handful of large scale installations, as well as smaller builds, it works very well, much better than the hardware store stuff. I like this stuff in particular the most-

https://www.acrylite.co/satinice-optimum-light-diffusion-colorless-0d010-df.html

With this one being a good option as well-

https://www.acrylite.co/satinice-optimum-light-diffusion-wd852-df.html


It works very well, but with any diffusion panel you need a few inches at least (six or more is better) between the emitters and the panel for good mixing.

 

[Saveafish]

Here.

 

[Matt Carden]

I was planning on using eggcrate as a cover for jumping fish. The eggcrate would be 5-6 inches from the bottom of light. That would be nice if it also worked to diffuse my light.