Algae wafer getting a "film" on it that makes it buoyant...?

[j250nyahweh]

We have a 20 gallon tropical tank with a golden pleco and we've recently noticed that when an algae wafer has been in the tank for the better part of a day, a white/clear film forms around it until the wafer becomes buoyant enough to float to the surface of the water. We've had the tank for quite a while and this only recently started happening. I tested the water and everything tested normal and safe so I'm not sure what could be causing.

One other little fun fact is that we've now got a growth of what I think are black worm larvae (they are read), as we've fed other fish in the tank black worms and they don't eat them all so I'm guessing they are making like bunnies. These little red worms will pop up out of the substrate around the wafer, and I would think this would be my answer, but often times the wafers will get that film even when we don't see any of the worms around it at all.

Any ideas what else might be causing this? And as a bonus, does anyone know if the the worms can upset the balance of the water conditions? I siphon them up about once a week when I do water changes but I imagins that's never going to be enough to get rid of them. Thanks! Sorry this is so long

[dbosman]

The brand of the algae wafer would be interesting.
Since the film forms over time, it would seem to be oils from the wafer migrating to the surface. It also seems they aren't getting eaten in a day.

I suggest breaking one wafer in to quarters or halves and see what happens.

[bignellm]

I know the Hikari wafers just disintegrate when not eaten. Seems very much like what dbosman said.