Koi Health and Supplies » Water Treatments » Dechlorinator Crystals 2 Lbs.

Whenever you do a water change, make sure to add some dechlorinator before refilling the pond.

Under normal use it is generally not necessary to add dechlorinator to the pond each time the auto-fill comes on because it is only replacing such a small percentage of water.

Again, the exception would be if you were replacing more than 10% of the pond water at any one time.