Thick clear oil slick floating on top of water!

[gypsie32]

I have a 90 gal reef tank, that over the last week has had a thick clear fluid floating on top of my water. I have cleared it off twice and I can not figure out what it is. I tested the water and everything was good, the only thing I can think of is maybe one of the corals is excreting something...I know my bubble coral has not been looking good but everything else is great!
bubble coral
torch coral
frogspawn coral
xenia coral
button poloyps
If anyone has any ideas as to what it may be please let me know...the tank looks great other then the stuff floating on the surface...only has done it twice

 

[spmnarciso]

Probably from food, but many of us have had that at the beginning, just place a powerhead to agitate the surface...helps for gas exhange and cooling.

 

[ty_05_f]

Do you have a protein skimmer? Just agitate the water more like spm said and it should go away.

 

[gypsie32]

My tank has been up and running for over a year and I have never had this problem...i run 4 powerheads and a euro-reef skimmer...is it possible one of my corals excreted something into the water that would cause this....all water perimeters are good...thanks

 

[big911dog]

i had a water giant pump leak oil one time just before it died. all PH's and pump running ok?

 

[dburr]

Does the bubble look like it's dying on any of the polyps? Got a pic?
All other corals OK?