Fishless Cycle - unknown substance on gravel, media, and plants

[DialUp]

My 55 gallon tank is undergoing a fishless cycle. After two months, ammonia and nitrites are at zero every night, with nitrates between 20~40 PPM. PH is around 7.0. I have three anubias plants on driftwood, and use a Oase Biomaster 350, with most of the sponge media replaced with ceramics rings.

I was planning on introducing my single goldfish into the tank this weekend, so went to my LFS, and showed them the following pictures of this substance on my gravel, plants, and filter media. The stuff doesn't move and comes off with a wipe. Initially was advised to dump everything and start from scratch, or I could try solution that treats tanks for worms.
Anyone seen anything like this before? Pics attached.
I would rather avoid having to do a new cycle, so any tips on making sure this thing is safe for my fish would be greatly appreciated.

 

[SaraB]

Looks like harmless plant debris. Maybe increase the flow in your tank so your filter can pick it up. I'm currently going through something similar. Someone suggested a powerhead or an airstone.

 

[King Fisher]

Do they move? Looks like debri as stated above. Use a gravel vac and clean it up. I don't see a need to start over right now.

 

[DialUp]

No they don't move (though i do have little squiggly worm looking things in there). The stuff on the gravel won't come off with the vac, but the dusty looking stuff does. The green stuff on the gravel sure looks like growth.

 

[King Fisher]

What do the squiggly worm things look like? The other stuff looks like just debris.

 

[DialUp]

They look like very very small white lines that swim, some have dark tips. I think it might be gnats or something, because i find them dead in the tank floating at the top. Or maybe something else.

 

[King Fisher]

Sounds like detritus worms. Harmless.