What worms are these

[PeterEde]

What worm builds these tubes?
Reducing depth of sand bed and the sand is full of these tubes.
Syruggled with nitrate for a long time. Currently 30 ppm but dosing 90ml vinegar a day. Crazy.
My last idea is to reduce depth of sandbed. Maybe leaching nitrates?
Ill keep ½ what i have.

 

[Crabs McJones]

Spionid worm are the only ones I know of that use substrate to build a tube