scum layer on the top of water
 

I have never had this occur. Is there a way I can get rid of this? I have a RenaXP4 canister filter and no overflows on a 175gal glass tank. I have a old skimmer from a saltwater tank I could use. Would this be a solution?

do you have a picture? That would definetly help everyone out to help you. Are you sure its scum? It may just be tiny little bubbles. Pic please :D

I've had this happen before on one of my tanks that was a bit overcrowded. I used a siphon to remove most of it, then kept doing 1/3 water changes for a few consecutive days days. I never found out what had caused it though.

lay some kitchen roll on the top of the water, let it absorb the scum and simply remove.

filter!

This is a buildup of protein on the top. This can easily be removed by placing a paper towel on the surface absorbing it. This can easily be prevented by adding some surface agitation, such as a airstone connected to an airpump or a powerhead so that there is some kind of motion on the surface of the water.

This does not harm the fish/plants, but is just unsightly.

i agree with eddie- it can be calcium build u aswell, when the surface is not broken it can lead so a skin occuring. You can as eddie says aggitate surface or introduce surface dwelling fish such as mollies that skim the surface of the water.

I just crank up the airpump and it usually disappears within 10 minutes... I dunno if they are all ending up on my hood or something but the water is clear! :D