My neighbor and I both have koi ponds. In search of start up equipment we both ended up with The Pond Guy. Our most recent search was for a PondVac to remove bottom slug without wasting water. All the pond vacuums dump the water over the ground. When we ask the Pond Guy about reusing the water they were quick to tell us we shouldn't due to introducing algae back into the pond. We will filter the return water to try and prevent this from occurring.