Powder Blue Tang, Don't like his reflection

[fppf]

Well I have had my Powder Blue Tang for 5 months now.
He is doing GREAT! What a wonderful fish.

Only one little problem that started the last few days.
He REALLY does NOT like his reflection that he sees in the glass at night. I shift the "daytime" for them to the evening because thats when I'm home the most. Well we like watching TV in the dark (better big screen viewing) and the lights in the tank make a mirror. Well after a while he starts getting really MAD and will start attacking the glass with his tang. You can hear it in the room when he hits the glass.

So for now I'm keeping some lights on in the room so he can see out. Any ideas on how to fix this issue. I'm sure its not good for him to be hitting the glass. I'm sure its not good for the glass too! :roll:

Did I say how beautiful he is! :-D

[Zack]

I have never had this issue with a blue tang, but how big is your tank? Has anyone else heard of this before?

[Doctor_Reef]

Not to that extent.....Wow...

[fppf]

Maybe I will take a video and post it.
As soon as I turn lights on in the room he chills out.

I was thinking about it a little more my self. When I go to reef lighting and make my hood I think I will mount a standard tube just in front of the tank so it will shine through the front of the tank. This should solve the mirror issue and they will be able to see me as good as I can see them. I really do think the fish like seeing out of the tank. Sometimes I think they watch me as much as I watch them.

[Telco Guy]

The light just outside the glass will not help. He is seaing the reflection because the rest of the room is dark. The reflection is always there, but when the rest of the room is lit up there is enough background clutter so he doesn't notice his reflection.

[fppf]

Well the reason its acting like a mirror is because its very bright inside and dark outside. So by putting a light that shines through the glass from the outside it should make the mirror go away.

[Telco Guy]

No, that's not how it works, but you can try it if you want. ;)

[fppf]

Ok, well then how does it work?

[Telco Guy]

Well, without getting in to the real physics of it, the reflection is always there. It's just faint and becomes more noticeable when the background is dark and there is more contrast.

[fppf]

No, the reflection will not always be there. When the light in the room is higher or the same as the light in the room the fish will be able to see out of the tank into the room. When the ligh in the tank is higher than the room the fish wont be able to see in the room, they will see there reflection. When the light in the room is greater than in the tank you see your reflection. You are correct as the light balance changes the reflection will greater or less intense.

Its just like windows in a house. During the day people can't see in your windows. At night when you have the lights on in the house you can't see out but people can see in. At dusk it goes both ways.

So the idea is to put a light that would simulate lights in the room without lighting up the room a lot.

[Telco Guy]

Well, we are getting a bit off the main topic here, but the light in the room doesn't change the physics that cause the reflection in the glass. Trust me on that. ;) So, unless your light on the outside of the glass lights up the rest of the room, you won't get what you want.

Don't get me wrong, I'm not just trying to argue with you on this. I'm just saying that you may want to test your theory prior to going to the trouble of building the hood. ;)

If you'd like I can look up the physics onthis and post a link, but from my physics classes that I took in college I know that placing a light outside the tank doesn't not have an affect on the way photons are reflected off of a piece of glass.

[Telco Guy]

Ok, here's a page that discribes the reflection properties of glass.

http://www.astro.washington.edu/tmurphy/phys110/faqs/AB06.05.html

[fppf]

Hummm
Well you did raise a point, a light on the tank that is in front of the glass may have to shallow of angle of incidence and just bounce off.

You are correct that putting a light in the room will not change the amount of reflection inside the tank. However you can wash it out. Snells laws depict how light bends and reflects when entering different matterials.

I just can't think of anyother way to stop this. I will take a video tonight and post it. He really gets MAD!

You posted that link as I was typing, thanks it said what I typed.