Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Hydrated Lime vs Rotenone to Nuke a pond

I've never done a restart on a pond but have wondered what the pros and cons are of using rotenone vs hydrated lime. As far as I can tell, both methods work but rotenone requires permits, licensed personnel, etc. and anybody can use hydrated lime?

They both work. In natural low alkalinity ponds hydrated lime will not cause long term problems with base accumulation. I don't know if that is true in high natural alkalinity ponds.

Thanks. Assuming neither cause lasting effects and both are lethal, how to decide which one to use?

Bill, how big's the pond, and would you drop the water level before you treated it?

I've done both, and although being far less work, the rotenone is more expensive, and works best when distributed evenly throughout the water table. That means pumps, prop wash from a boat, etc.

Hydrated lime would probably be cheaper (depending on the amount needed), but it is messy. It can be mixed as a slurry, and sprayed on the water's surface.

Thanks Al,

I'm not nuking a pond; just educating myself on the process.

As with everything pond related it seems "it depends" applies as to whether you use hydrated lime or rotenone. My take a way so far is neither method is fool proof and needs to be done carefully. The other take away is rotenone requires a pro for access to the rotrnone and its application while hydrated lime is something the DIY guy can do.

Does rotenone require a permit from gov. to assure there is no downstream kill before you can nuke your pond?

When we rehabbed my first pond in August 2015, we drained it down to a puddle and dozed it dry of sludge. It sat dry for a week baking in the hot August sun, then slowly started to fill from rain. I am sure that took out all the small GSF that were in there.

I vote for Rotenone, but then I have a license.

From my perspective, it's easier to do and requires less equipment. If you are pushing the reset button, and you drain down the pond to apply less hydrated lime, ANY small puddle that is missed could harbor an unwanted fish that could survive.

With Rotenone, just drain the pond down but leave plenty of water in there to allow you to get a boat in there. Use subsurface injection to treat the deeper water first, driving the fish to the surface. Start in the middle of the pond, treating the surface water, moving to the shore, trapping the fish there.

In a small pond, or a pond that might not fill back up quickly with water, I don't think there is a reason to use hydrated lime.

In FireIsHot's case, he could have nuked his small pond without removing any of the water, and 2 gallons or less of Rotenone would have done it.