Hey so I saw small white spots thinking it was pineapple sponge growing. A month later I pulled out the filter and found this, asked my local fish guy what he thinks and he didn’t know, hoping someone else could tell me what this is….
Agree on Cluster of pineapple sponge. Can be from new rock, new sand, from tap water if used and expired or leaking Di Resin cartridges.
These are short lived and will dissipate as silicates reduce. You can peel them off with the edge of a credit card into a net if they are too many
They are not harmful and cherish algae if they get any