What is this? (I've never seen it before)

[fish4phil]

I have a finished fishless cycled tank (been 5 weeks) 10 gallon, used pure ammonia, no fish food. I have plastic plants on the bottom, floating Amazon Frogbit plants on the top, and a HOB filter. Still no fish in the tank. The tank is covered. 78 degrees. Lighting 10 hours a day. 2 weeks ago I rinsed the filter in old tank water. The only thing in the filter is AquaClear BioMax and a coarse sponge.

Now I'm seeing a lot of gross stuff in my tank, on the bottom of the tank primarily, and stuck in the roots of my floating tank. When you're looking at the picture, know I painting the bottom outside of the tank blank, and have some suction cup plants - that's it, that's all you're supposed to be seeing. What in the world is this? My room isn't that dusty! I'm worried about adding fish to this and having them eat this.

 

[pip walters]

The beneficial bacteria have a lifespan and as they multiply,nsome will die off, forming a film of dead matter. This film often coats the inside of pipework etc as layers of dead bacteria develop. This film often breaks up and is then forced out of the pipework

Just siphon it out when you do a water change.

 

[fish4phil]

Very interesting! So that's dead bacteria, so much of it that it becomes visible? Thanks for the info

 

[t4runnr]

Sometimes in my tank, the film comes out of the return nozzles and the fish go nuts for the stuff. More so than the food that I feed. So every now and then I'll shake up the return tubes to loosen them up and the fish gets a treat.