In any case, here's the Rx for taking out hydra and nematodes:
1. Copper Sulfate (CopperSafe), if you have nothing wanted in the tank that is copper sensitive.*
` A. Remove all carbon first!
` B. Let the copper do its job for a few days. Read the label!
` C. Copper is very hard to remove completely once in the tank.
`` a. Carbon helps but change it every 3 days for two weeks. It saturates quickly.
* Copper Sulfate will kill any invertebrate!
2. Water changes! 50% daily or as often as you can stand.
3. Vacuuming of visible hydra and substrate with every water change.
4. Reduce feeding. These organisms can't live very long with nothing to eat.
5. Gouramis, Mollies, and Plecos will eat them!