Its most likely bio film. It shouldnt be a problem. Some algae eaters and snails will eat it.what causes a white film on the inside
glass ?
There is no such thing as a fish sponge. It is just a term we use for a clean soap free sponge you use on the fish tank.
Any sponge that does not have soap, disinfectant or anything added to it can be a fish sponge.
Unfortunately most of the koalas were killed in a horrible way during the fires. There was some really graphic footage on TV here and I still have nightmares about it.
However, the remaining koalas will benefit from donations that help to pay for burn creams and ointments to help them heal. Thankyou for helping the poor little animals.