Painting to increase PAR reading?

[Pazernaker]

Hey guys,

I have a pretty basic light question I can't seem to find a clear answer on. Is there a high gloss coating (Silver? White?) that you can paint the back of a tank with to increase PAR readings? I was planning on putting some black gloss PlastiDip on the back glass this week when I thought maybe something more reflective and less absorbing of light might benefit the tank better. If it only gives a couple % increase in PAR, then I'll stick with black for the look, but thought I should ask before I commit.

Thanks!
Ryan

 

[Jedi1199]

First off.... Black absorbs light. Even a gloss black will not reflect much light.

I am not much of a fan of black backgrounds personally. I prefer blue. I think it showcases more of the inhabitants than black.

Now, as for increasing par? Here is a simple trick to see what works. Go to the pet store and get a piece of the blue and black plastic background sheet. Test your par with both sides and see what works. They are a high gloss background so it will give you a decent idea of what direction you want to go.

 

[Chrisv.]

Hey guys,

I have a pretty basic light question I can't seem to find a clear answer on. Is there a high gloss coating (Silver? White?) that you can paint the back of a tank with to increase PAR readings? I was planning on putting some black gloss PlastiDip on the back glass this week when I thought maybe something more reflective and less absorbing of light might benefit the tank better. If it only gives a couple % increase in PAR, then I'll stick with black for the look, but thought I should ask before I commit.

Thanks!
Ryan

There was a nice video that bulk reef posted about the impact of different coatings on par.

Might get as much benefit from making sure you have no biofilm on the glass. Clean glass itself reflects a lot of light.

 

[Koh23]

Black background will absorb some reflection, white will reflect some more.

What exactly is "some"..... Hard to tell without precise measuring....

Also dirty glass reflect less than clean, so dirty black glass again reflect less than dirty white glass...

But, for all this to be effective and really make noticeable difference, white, chrome, silver,whatewer reflecting coating is, it had to be on inside of tank.

Back of glass will absorb/reflect much less than glass from inside of tank.

 

[oreo54]

Hey guys,

I have a pretty basic light question I can't seem to find a clear answer on. Is there a high gloss coating (Silver? White?) that you can paint the back of a tank with to increase PAR readings? I was planning on putting some black gloss PlastiDip on the back glass this week when I thought maybe something more reflective and less absorbing of light might benefit the tank better. If it only gives a couple % increase in PAR, then I'll stick with black for the look, but thought I should ask before I commit.

Thanks!
Ryan

 

[Freenow54]

Interested in this as well. Black absorbs for sure. I have both tanks with black I read about Blue I should unless someone else will measure the difference. have an Apogee but have yet to do readings dealing with other issues still. However NO paint! I used simple cheap gardening ground cloth

 

[Pazernaker]

Thanks for all the input! I totally understand that black absorbs, but was curious about other people's gains from using different colors/gloss level. If it was only a little, then I'd be more inclined to stick with the black traditional color, but if it was a decent amount, I'd reconsider.

I don't have a PAR meter, as that price tag seems to hurt, otherwise I'd test it myself with a couple different colors since plastidip can be removed. Thanks for the help as always, guys!

 

[Pazernaker]

Black background will absorb some reflection, white will reflect some more.

What exactly is "some"..... Hard to tell without precise measuring....

Also dirty glass reflect less than clean, so dirty black glass again reflect less than dirty white glass...

But, for all this to be effective and really make noticeable difference, white, chrome, silver,whatewer reflecting coating is, it had to be on inside of tank.

Back of glass will absorb/reflect much less than glass from inside of tank.

Why does it have to be on the inside of the glass? Glass has an absorption rate of 2-10%, so most of the light would still be reflected/transmitted back into the tank without being absorbed by the glass.

 

[oreo54]

Why does it have to be on the inside of the glass? Glass has an absorption rate of 2-10%, so most of the light would still be reflected/transmitted back into the tank without being absorbed by the glass.

You need to watch the vid abov.
Simple explanation, when you destroy the glass/air gap in the back of the tank that eliminates the natural reflection back from glass in air.

Nothing on the back "increases" par over plain bare glass.

Now if you put say something "inside" you eliminate any plain glass losses.
Not really worth the effort and risk though..

Of course something like a mirror (unless first surface) has it's own glass interface..

Complicated and I don't exactly grasp all the innuendo but bottom line.. Plain unpainted glass is pretty much best case..at least the easiest.

If one wants say a black background but doesn't want to lose par.. keep the air gap using like foam core painted and spacers.

Of course that isn't your goal.

 

[Koh23]

Well, if you put "something" behind "something else", you reduce or improve ability of "something else" to reflect light.

In this case, "something else" is paint, "something" is glass. You need to calculate glass thickness into matter, so, we have something somewhat reflective behing 10,15 or 20mm of glass.... In this case, glass is reflective surface, not anything behind it.

As for paint, or vinyl goes, the "reflective" side (lets call it that way) is one that is on outside of object, not inside. So in case of glass, paint or vinyl needs to be applied to inner surface, so that light hits that paint, not glass.....

Yes, as above, black/dark paint will absorb and diminish glass ability to reflect light at some degree, same as white/light color will increase reflection on outside layer of glass, primary because the light cannot pass painted surface, and not because reflective properties of underside of white color.

Now, this is all theory, i believe that benefits/downsides of painting glass is really no concern, there is little loss/gain, so it all comes to personal visual preferences....