New guests? Hydroids?

[smitty]

I noticed today that I have new guests in my RCS bare tank. This tank is just a holding tank while another tank is being set up, everything in this tank is from older established tanks that don't visibly have these guys in it. What are these guys and is it reason for concern?

[ronv]

Hydra... Bare tank meaning no fish? Bleach the tank to get rid of those nasty buggers.

[smitty]

There is some java, snails, and a handful of shrimp. Would peroxide work? Shrimp out and copper (snails could use culling)?