Algea 'tumbleweed' balls?

[RBarth]

6 year established tank. P .05, N 12, Alk 8.3. Have made zero changes and recently noticed my sand was clumping with what appeared to be algea...everything kinda sticking together on the sandbed. Does not have a Dino look. Removed most of the sand and rinsed in peroxide and put back in. Its like these small algea balls or spores that just spring up. I found a pic online of what they look like but the poster didn't get a response. Any ideas?

 

[RBarth]

Differnet pics

 

[Subsea]

Those interconnecting roots look vicious & invasive.

Were the last pictures after gravel peroxide wash?

If some substrate was left in tank, I would expect those things to still be in the tank. How big is tank?

Consider a UV sweep.

“A UV sweep in a reef aquarium uses a specialized manual Sand Bed UV Sweeper tool to target and sterilize benthic pests like dinoflagellates and diatoms on the sand surface. It safely controls outbreaks without chemical additives or disrupting the deep sand bed microbiome. [1, 2]”

 

[RBarth]

Yes, after the peroxide wash. I had used the UV sweeper first to no avail. That's when I decided to scoop the sand and wash it. It's so strange...like u can pick up a 'spore' and it all clumps the substrate together. Tank is a IM 60SR.

 

[Subsea]

I can’t help with name. It’s in your substrate and you need it removed. Stuff like that can come in with frags or fish poop from new fish.

I highly recommend you rip clean all of your substrate.

 

[RBarth]

Ugggggh. Haven't added a fish or frag in over a year. Was debating on Reef Flux but....