what is in my tank now?

[stillwearingaredribbon]

Can you see the little white bits in the glass
They look like lines but they are moving
I am having a terrible snail problem, are they going to grow into snails?
Would a better filter help
Its a cold water tank with minnow in it
TIA

They look like they might be planaria (flat worms). Most of them are harmless, especially to adult fish, but they indicate a possible dip in water quality and probable over-feeding. If you cut down on feeding a bit and give the gravel a good vacuum then that will help, and it will cut down on the snail population too.

Have you got a water test kit?