Questions - Need some input

Our tank seems to have developed a slight film on the waters surface.All thr waters psrameters are good but the film doesn't
Seem to go into the overflows. Any ideas?
Any help is apprrciated.

Question for all the addicts using a Refugium. If there is algae starting to grow in the Refugium on the glass, will adding a turbo snail in help with keeping it under control? Will they leave the cheato alone?

So my tank has been going pretty well. Almost too well. My Montipora has been putting on a measured growth weekly, gorgonians open and growing, even my goniopora has grown and attached to nearby rocks.

But I've always been unhappy with the tank.

Last week listening to Gary & Christine's Reef Threads podcast (which is a nice replacement to the Reef Addicts podcast since it is updated like.....NEVER! I'm looking at you Melev!) ...

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Are filter socks worth having in a sump to catch what comes out of the drain line? My sump is running with a bio pellet reactor, reef octopus skimmer, phosban reactor, Refugium with LR, deep sand bed and cheato. Should I keep using the filter sock or run without it? Anyone with thought, I would like to hear them...