Rena Filstar XP1 canister filter

[Ronny#66]

I am using one of these on my 25 gal reef tank. Every monthIhave been takeing it apart to rinse foam pads one pad biweekly. When I put filter back together and flip handle to fill chamber back with tank water. A white egg white like matter blows out of filter outlet what a mess but snails and crabs go nuts over it. I finaly figured it's the slime in hoss and maybe head of pump on canister housing that you can't get at it's sealed. My ? is is this stuff bad for tank It does it every time I maintain the filter.