| | Re: Harvesting local flora?
You can dip the plants in a copper solution and then rinse in saltwater to kill most stuff. Probably wouldn't affect algae, but I typically avoid that by selecting carefully at the river. The best solution is to quarantine them for a little while.
Most of the hitchhikers I've gotten have been pretty benign, but there are some freaky things on occasion. In my 6 gallon there is a pretty sizable insect that showed up (presumably much smaller) on one of the plants. It's neat, but it would be a nightmare if it was in a stocked tank!