Anyone ever diffuse a T5?

[Mark_C]

So with my current 4 bulb T5 setup, the top of my tank is sitting in about 380 PAR, the bottom around 180. Wee bit too high.
If I remove 2 bulbs, the top drops to 160ish. BIt too low.
If I try to run 3 bulbs, which would be perfect, no dice, the circuit on the light runs bulbs in pairs.

My light has a plastic cover between the bulbs and the tank.
Thinking of getting some glass frosting tape, or something like that, and trying to use it on the plastic to diffuse a bulb, or , or 3-4, to drop PAR a bit.

Anyone tried this before?

 

[ecam]

@Mark_C can you raise the fixture ?
Any diffusers will drop the par too much.

 

[MadReefer]

What about egg crate? Can cut out holes to suit your needs.

 

[hcker99]

grab some screen door mesh and attach it to the plastic splash guard on the light. The more layers you do the more it will difuse the light

 

[Sponge]

I like the screen door mesh idea. But yes you absolutely can diffuse the T5 in fact they make diffuser sleeves for fluorescent tubes that have a radiant design that you simply rotate the sleeve to get the amount of diffusion you want.

 

[ecam]

The black screen mesh will work. But when I tried it for looks. I lost a lot par. But since your trying to reduce give it a shot

 

[Sponge]

A quick search and I found one called a matrix pattern. And there are others. They are T5 plastic sleeves that go over the tube and a simple rotation of the sleeve adjust the amount of diffusion

 

[Sponge]

What length graduated diffuser do you need. I found a four foot one for 12 bucks

 

[ecam]

The black screen mesh will work. But when I tried it for looks. I lost a lot par. But since your trying to reduce give it a shot

 

[Mark_C]

Cool deal folks. Mark, great idea, I’ll give it a go. Will use nylon to avoid rust I guess. Sponge, these are 36”, Ill look into sleeves as well. Thanks to all.

 

[amado]

I would try to raise the T5 if this is not easily done. Then I would leave it.
if the spread is good I would leave it. Some sps like that high par 380. I would move the corAls that don’t like that high par and put them at a lower par. The t5 will drop in power after a few months. You will lose some par and after a years you can lose even more. Some people would kill to get 380 par lol the corals can get use to it. Run your lights for less hours. For reference my top rocks get around 350 par.

you also need to remember when your corals grow they will cover the light and corals in the bottom would get less light.
this is what LED does best. Right now if you had LEds all you had to do is run your lights at 80% less. T5 don’t give you that option.
If you want a mixed reef with more lps and soft corals you have to move the t5 to 6-10” off the tank so you need a new mount.
I wouldn’t diffuse t5 lights.

 

[jgraz]

I would try to raise the T5 if this is not easily done. Then I would leave it.
if the spread is good I would leave it. Some sps like that high par 380. I would move the corAls that don’t like that high par and put them at a lower par. The t5 will drop in power after a few months. You will lose some par and after a years you can lose even more. Some people would kill to get 380 par lol the corals can get use to it. Run your lights for less hours. For reference my top rocks get around 350 par.

you also need to remember when your corals grow they will cover the light and corals in the bottom would get less light.
this is what LED does best. Right now if you had LEds all you had to do is run your lights at 80% less. T5 don’t give you that option.
If you want a mixed reef with more lps and soft corals you have to move the t5 to 6-10” off the tank so you need a new mount.
I wouldn’t diffuse t5 lights.

Pretty much sums it up.
My guess is too much light to quickly.
I've been toying with mine too. I have 2 blue+ bulbs going from 10-10, then I had the other 2 bulbs, blue+/coral+ going 12-16. All looked good coral wise,, but I wanted to increase the time I had all 4 going. So I started bumping up 1 hour per week to get to.7 hours. No dice, after 3 weeks I started to.bleach things and immediately went backed down on my hours. In short order I watched my colors start coming back in a week or so.
You can diffuse the light with screens, but keep it temporary and only for acclamation purposes.

 

[Sponge]

Not cheap but they DO make dim-able T5 fixtures. But I am curious... how many inches off the water are the lights.

 

[Mark_C]

Well, the height is part of the problem. They’re about 6” off the water but thats the size of the mounting legs. Also, any higher and I have to worry about light spillover into the rear chamber.

 

[amado]

Well, the height is part of the problem. They’re about 6” off the water but thats the size of the mounting legs. Also, any higher and I have to worry about light spillover into the rear chamber.

I have seen these lights and I would say leave it how it is. Wait a few weeks before you make any changes. Now if you can get another mount having them a little higher will mean you don’t have to move the lights to maintain the tank.

 

[Sponge]

Well, the height is part of the problem. They’re about 6” off the water but thats the size of the mounting legs. Also, any higher and I have to worry about light spillover into the rear chamber.

Are you able to measure PAR at any height change you can make temporarily. Like if one more inch works. You know... it fits and puts the PAR where you want it. Could we possibly 3D print new mount leggs?

 

[amado]

Not cheap but they DO make dim-able T5 fixtures. But I am curious... how many inches off the water are the lights.

yeah they are a lot more expensive

 

[Mark_C]

Think I got it.
As suggested I went out and bought some black fiberglass window screen.
Initially I put it over the entire splash cover and PAR levels dropped considerably across the tank with the center of the tank dropping from 380 to 220 at the top rock level and from 220 to 105 at the sand.
So, looking at the PAR, the highest levels were in the middle third of the tank.
I cut the screen so that a piece fit over the mid 1/3 of the splash screen (and was about 1-2" in from each side).
Now center rock top is 300 as an average across the tank, sand bed is 200 average across the tank.
Happy with this. Thanks for the help folks!

And, Mr Sponge. When next we meet I'd love to discuss slightly larger (and sturdier) legs/stand for the unit.

 

[Mark_C]

And here's our numbers.
Top number is pre-screen.
Bottom number is screen in place.



Now I just need to find a T5 schedule, and maybe back up a bit on lighting times.

 

[amado]

And here's our numbers.
Top number is pre-screen.
Bottom number is screen in place.

View attachment 31345

Now I just need to find a T5 schedule, and maybe back up a bit on lighting times.

I would have no problem with the original par. I don’t think you need a screen. I am glad you solved your problem.