I had the same problem, but I got a small surface skimmer that fluval makes.
I costs about $10 so its rather cheap. It simply plugs into your hose on the
canister intake, and continuosly skims the surface for any debris and scum,
sucking it into the canister filter where it is consumed by our friends the
bacteria. I've had it for about a year now, and never had any problems with
surface scum or floating debris.

I'm sure there are other manufacturers of similar products, but so far, I've
just found this one. And at $10, I'm not looking any further! :-)

Good luck!

/Mathias

"BruceKGeist" skrev i meddelandet
...
Will a UV strelizer help with surface scum? No matter what I do, I get a
pretty thick surface scum by the end of the week.

Also, how does one decide on what size UV sterilizer to get? Any specific
recommendations for a 135 gallon tank?

Thanks in advance..

-Bruce Geist