OK,
so I know this is resurrecting an old thread, but I've got the same problem now. Not QUITE as extensive as the pictures you posted, but the whole substrate is housing these tubifex worms, who stick their top half out, and zip back into the substrate way too fast to catch with a large tweezer.
I also tried vacuuming the substrate, and figured I'd get a ton, but was really surprised at how few ended up in the "dump" bucket, once the water cleared.
Now here's the weird part - this tank (a 30 g. low tech planted w/ a soil underlayer and Soilmaster Select as the top layer) is home to several geriatric harlequin rasboras, several dwarf cajun crays, a bunch of cherry shrimp, and two corys! I put the cories into this tank hoping they'd eat the worms. Then I added the crays hoping THEY would eat the worms. Either they're too fast for the other inhabitants to catch, or they are so dense that some predation doesn't even make a dent.
So what did you finally do with this tank? The little waving colony is starting to really annoy me. Plus, my fiance hasn't been nearly as eager to watch my tank with me since I pointed out the worms to him, LOL!
Any suggestions on what to do? I'm up against some similar issues, since this tank houses my growing cherry shrimp population - its heavily planted, and there are lots of places for young shrimp to hide.
Perhaps a Sparkling Gourami as a clean-up crew? They're fierce little hunters, and will probably pick off some baby cherry shrimp, but I've got a bunch of large frequently-berried adults, so if they can get the worms, I'd be willing to lose a wave of babies.
Any other thoughts on this?
Thanks much!
-Jane