Taken from: Koi.com.my

How Much to Use

1 gram of Zeolite will remove 1.5milligrams of ammonia from a liter of water. Take an Ammonia reading of your pond in PPM (parts per million). Divide by 1.5. Multiply by the numbers of Liters in your pond (3.78 Liters = 1 Gallon). The final volume is the number of grams needed to treat your pond (1 level teaspoon of Zeolite equals 7 Grams).

Recharging Zeolite
You can also recharge Zeolite to about 78% of it's normal adsorption rate by soaking it in a salt water solution (1lb. of salt to 3 gals. of Water) for 9 hours or more. Remember to rinse the Zeolite before returning it to the pond.