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A Fresh Clean Pond

Hurth Waterscapes Spring Pond Clean Out

Pond Cleanout Tips – Fish Health – How NOT to kill them.

Many of you will choose to clean out your own pond.  If you are planning this, check out our pond cleaning video and our pond cleaning page for full instructions.  This little article is all about the fish.  Your fish have made it through the long winter and they are weak at this time of the year, let’s do our best not to kill them now.

Holding Tank

  • You’ll need a holding tank for the fish.  The bigger the better for the health of your fish.
  • Unless it is really cold outside, you’ll probably want to have an aerator in the holding tank to keep the oxygen levels high in the holding tank.
  • Place the tank on a fairly level surface somewhere near the pond.  If it is a cool cloudy day, location won’t matter much, but if it is hot and sunny, you’ll want the tank in a shaded area so that the water doesn’t heat up too much.

Pumping Down the Pond and Removing the Fish

  • Do not start walking around in your pond stirring up the debris and freaking out the fish.
  • When you first begin to pump the water out of the pond, carefully place your pump on an upper level and pump some of the cleanest water into the tank where you will keep the fish during the clean out.
  • Have a net ready to cover the fish tank so that the fish don’t jump out while you are cleaning the pond.
  • Don’t even try to catch the fish until you have most of the water out of the pond.  You want the fish to remain calm and the more you chase them around, the more energy the use and the more freaked out they get.
  • Once the water level is just deep enough where they can still swim, it is very easy to catch them and transfer them to the holding tank.
  • Keep an eye open while you are pumping down the water.  Usually the fish will instinctively move down to the lowest level as the pond is emptying, but occasionally you’ll have some that get caught up on an upper level in the plants or under the leaves and debris.  You’ll need to get these stranded fish to the holding tank as soon as possible.
  • I usually have a five gallon pail of water that I use to transfer the fish to the tank.  It makes it easy to collect the smaller fish and eliminates a lot of trips back and forth to the tank.
  • Of course the larger fish will need to be transferred immediately to the tank.  When doing so, be sure to move quickly and cover the net so that they don’t jump out of the net on the way to the tank.
  • Never throw fish from the pond to the tank, remember the less stress the better.

Filling the Pond and Returning the Fish

  • Once you finish your pond cleaning, it is time to start filling the pond and return the fish to their home.
  • Here in Wisconsin we are usually cleaning ponds in April or May, so it is usually still fairly cool outside and the water in the holding tank is usually fairly close to the same temperature as the water coming out of the tap that we are using to fill the pond.
  • Your fish can handle very warm and very cold temperatures, but a rapid change in temperature can put them into shock and kill them.
  • As the air temperatures warm up, it becomes more and more critical to match the holding tank water temperature to the temperature in the pond before putting the fish back into the pond.
  • You can use a water thermometer if you’d like, but I have had really good luck just using my hand to test the water.  If the water feels significantly different to you then it is probably too much of a difference for your fish.
  • If the water is more than a few degrees different, you can run tap water into the tank with the fish to slowly cool it down or warm it up.  Since you are re-introducing your fish after the clean out, the new water in the pond has just come out of the tap, so tap water will help to slowly change the temps of the tank water.  Just don’t change it too quickly.
  • Most of the time, in cool temperatures, we can just start to fill the pond and when it gets full enough for the fish to swim we pump the holding tank water back into the pond and re-introduce the fish at the same time.
  • Another way to acclimate the fish is to float their container in the pond water for a period of time until the water temps have equalized.  You can use buckets or plastic bags full of the holding tank water and the fish to do this.  Just float the container in the pond and test it with your hand until the temperatures feel close to you.
  • If you have your doubt about the water temperatures, it is a good idea to introduce one fish to see how it reacts to the new water.  If it looks fine after a few minutes, you should be safe adding the other fish.
  • As you add fish back to the pond, take a minute to look at the fish.  If there are any fish with open sores on their bodies, it is probably better not to put them back into the pond with your other fish.
  • This is also a good time to eliminate any fish that you don’t want.  Oftentimes the goldfish population will just go crazy and overwhelm your pond if you don’t remove a few fish from time to time.  Here in Wisconsin I have not had this problem with Koi.
  • If you are filling the pond with city water you’ll need to add dechlorinator to the water.  The chlorine in city water can burn the gills of your fish.
  • The water in the freshly cleaned pond will contain plenty of oxygen for your fish, but you’ll want to start your pond’s water circulation as soon as you can to keep the aeration levels high.

That’s about it.  If you follow the steps above, you should have very few fish problems.

Have a great summer!

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