Blue / Green Water

[F4A]

A few months ago I changed my filter for a Tetra EX600 and all is well. However I have noticed since using this new filter my water goes slightly blue/green a week after a water change. All my bio media has now turned completely green. Maybe the filter part is just a coincidence but I'd like to find out whats causing it. Any ideas??

Also, the water pipes on this new filter are clear so I can see a build-up of grim on the inside. When I stop the filter and start it up again, most of this gushes out. Is this algae??

 

[armymp327]

could be Cyanobacteria, also known as blue green algae. Usually caused by over feeding or a dirty substrate i believe, im not very knowledgeable on Cyanobacteria but thats what i know about it

what size tank is this? and how long has it been set up? water change schedule? and do you clean the substrate well?