Glass or Plexyglass top?

[Ace25]

Sorry, but again, I see nothing pertaining to coral health there. All is says is "fish do better with more UV light", which I have to question on how much of a factor that really is for fish because many people run FO saltwater tanks with lights that put out little to no UV and have fish live 20+ years... and then it goes on to talk about ORP, which really doesn't have much to do with UV. ORP has to do with gas exchange, which ANY top on a tank would restrict, but UV and ORP shouldn't have much to do with each other. From everything I have read, corals react negatively the more UV they are exposed to, again, the reason why you must have a UV sheild on your metal halide bulbs to protect your corals from UV damage.

 

[jayghmi]

Dang! I am learning a lot from this thread. My personal experience is that when I removed my glass top to nothing, everything in my tank looked better. I do have a ton more evaporation, which forced me to by a RO unit, but topping off gives me something to do to my relatively mature tank.

I have had a clown jump to his death after being in my tank for about two years, so their is a downside. He may have jumped because he saw the stock channel because I never had a problem with him until then.

Bottom line is my tank seems healthier with nothing on it. If I were going to put something on it, it would be the plastic bird garden protection mentioned in another thread. I believe the plastic screen comes in both 1/4 inch and 1/2 inch square holes.

 

[Trigger334]

I was trying to find where this information came from. Here is a reference for this source.
http://www.americanaquariumproducts.com/basic_saltwater.html#lighting

 

[Narwhal72]

Not all UV is the same.

A metal halide lamp produces a degree of UVC (same as a UV sterilizer). Which would be very harmful to fish, corals, and humans. Even low wavelength UVB can be harmful. However high wavelength UVB and UVA are not harmful and help the body produce vitamin D. UV A and B penetrate water further than visible light and are able to be utilized by some photosynthetic pigments.

However unless you are using a lamp that produces UVA and UVB (Metal Halide or Actinic fluoresecent) then the point is moot. LED fixtures do not produce any UV of any type. Even the LED's that are so-called (UV) are actually 400 nm which is the border of visual and UVA and not really a UV light at all.

Any kind of top is going to attenuate or block light. The degree of which is determined by how well you keep it clean or how opaque it is.

Personally I would go with glass as it has better durability and reduced flex than anything else.

Andy