Zeolite adsorbs ammonia from fresh water, and releases any ammonia it contains when put into salt water.
To use it, simply get a mesh bag, stocking leg or something similar, and put the Zeolite into the bag. Put a rubber band around the end of the bag or tie it up somehow so the Zeolite doesn't come out.
Rinse the bag of Zeolite under tap water for a few seconds to wash out any white dust on it.
Put the bag of Zeolite into a power filter or air operated box filter and put the filter in the tank. Let it run until the ammonia levels have come down to 0 and then remove the Zeolite and put it into a bucket of salt water.
If you don't have room in the filter for a bag of Zeolite, hang the bag next the filter outlet so the water flows over the bag and it will work, just not as quickly.
You only leave the Zeolite in the tank until the ammonia is at 0, then you take the Zeolite out so the filter bacteria can eat any ammonia that is produced after that. If the ammonia levels go up again after that, you can put the Zeolite back into the tank. However, it should be used as a temporary measure and not used in tanks permanently because it stops the filter bacteria from developing.
If the ammonia level goes above 5ppm or the pH drops below 6.0, the cycling process can stall.
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To recharge the Zeolite, put the bag of Zeolite into a bucket of salt water and leave it there for 24-48 hours. Then remove the Zeolite from the salt water and rinse it under fresh water to wash off any salt. Allow the Zeolite to dry and put it in a plastic zip lock bag until you need it again, or re-use it straight after rinsing with freshwater.
If you have the Zeolite in an air operated box filter, or a power filter that is not used for the main tank, just put the filter (containing the Zeolite) in the bucket of salt water.
If the Zeolite is in a bag and not in a filter, put an airstone in the bucket of salt water to help circulate the salt water through the Zeolite. Make sure the bag is loose and the Zeolite can easily move around in the bag. Put the airstone underneath the bag, which should be hanging in the water.
The salt level should be about the same as seawater or a bit higher. You can use rock salt, sea salt or swimming pool salt to make up the salt water. Or go to the beach and bring back a bucket of sea water. Most people buy a bag of swimming pool salt from the hardware or pool shop and use that because it's cheap.
You can buy Hydrometers from pet shops or online and these tell you how much salt is in the water. There are 3 main types of Hydrometer.
1) Plastic Chamber Hydrometer. These are a clear plastic container about 4 inches long x 4 inches high x 1/2 inch wide. They have a plastic lever in the container and there are numbers on the side. You fill the container with salt water and the needle (plastic lever) floats up to whatever the salt level is and will point to a number. The number is the salt level.
2) Floating Glass Hydrometer. These are a thin glass tube and they have a mark near the top. You float them in the salt water and read the mark (number) on the glass bit where it is at the surface of the water.
3) Refractometer. These are the most accurate but also expensive. You put a drop of water on a small glass panel and look through an eye piece. There will be a line with numbers and you see these by looking through the eye piece. Whatever the number reads, is what the salt level is.
My personal choice is the plastic chamber hydrometer because they are tough, reliable and reasonably cheap, and easy to read. The glass hydrometers break too easily. The refractometer is expensive and needs to be calibrated quite regularly.